diff --git a/head/schema-typescript/test/inputs/schema/multi-source-1543/default/TopLevel.ts b/head/schema-typescript/test/inputs/schema/multi-source-1543/default/TopLevel.ts
new file mode 100644
index 0000000..c3f2b78
--- /dev/null
+++ b/head/schema-typescript/test/inputs/schema/multi-source-1543/default/TopLevel.ts
@@ -0,0 +1,219 @@
+// To parse this data:
+//
+//   import { Convert, OrderCustomer, TopLevel } from "./TopLevel";
+//
+//   const orderCustomer = Convert.toOrderCustomer(json);
+//   const topLevel = Convert.toTopLevel(json);
+//
+// These functions will throw an error if the JSON doesn't
+// match the expected interface, even if the JSON is valid.
+
+export interface TopLevel {
+    external_order_ref?: string;
+    info:                OrderCustomer;
+    [property: string]: unknown;
+}
+
+export interface OrderCustomer {
+    country?:     string;
+    email?:       string;
+    first_name?:  string;
+    last_name?:   string;
+    newsletter?:  string;
+    order_number: string;
+    phone?:       string;
+    post_code?:   string;
+    type?:        string;
+    [property: string]: unknown;
+}
+
+// Converts JSON strings to/from your types
+// and asserts the results of JSON.parse at runtime
+export class Convert {
+    public static toOrderCustomer(json: string): OrderCustomer {
+        return cast(JSON.parse(json), r("OrderCustomer"));
+    }
+
+    public static orderCustomerToJson(value: OrderCustomer): string {
+        return JSON.stringify(uncast(value, r("OrderCustomer")), null, 2);
+    }
+
+    public static toTopLevel(json: string): TopLevel {
+        return cast(JSON.parse(json), r("TopLevel"));
+    }
+
+    public static topLevelToJson(value: TopLevel): string {
+        return JSON.stringify(uncast(value, r("TopLevel")), null, 2);
+    }
+}
+
+function invalidValue(typ: any, val: any, key: any, parent: any = ''): never {
+    const prettyTyp = prettyTypeName(typ);
+    const parentText = parent ? ` on ${parent}` : '';
+    const keyText = key ? ` for key "${key}"` : '';
+    throw Error(`Invalid value${keyText}${parentText}. Expected ${prettyTyp} but got ${JSON.stringify(val)}`);
+}
+
+function prettyTypeName(typ: any): string {
+    if (Array.isArray(typ)) {
+        if (typ.length === 2 && typ[0] === undefined) {
+            return `an optional ${prettyTypeName(typ[1])}`;
+        } else {
+            return `one of [${typ.map(a => { return prettyTypeName(a); }).join(", ")}]`;
+        }
+    } else if (typeof typ === "object" && typ.literal !== undefined) {
+        return typ.literal;
+    } else {
+        return typeof typ;
+    }
+}
+
+function jsonToJSProps(typ: any): any {
+    if (typ.jsonToJS === undefined) {
+        const map: any = {};
+        typ.props.forEach((p: any) => map[p.json] = { key: p.js, typ: p.typ });
+        typ.jsonToJS = map;
+    }
+    return typ.jsonToJS;
+}
+
+function jsToJSONProps(typ: any): any {
+    if (typ.jsToJSON === undefined) {
+        const map: any = {};
+        typ.props.forEach((p: any) => map[p.js] = { key: p.json, typ: p.typ });
+        typ.jsToJSON = map;
+    }
+    return typ.jsToJSON;
+}
+
+function transform(val: any, typ: any, getProps: any, key: any = '', parent: any = ''): any {
+    function transformPrimitive(typ: string, val: any): any {
+        if (typeof typ === typeof val) return val;
+        return invalidValue(typ, val, key, parent);
+    }
+
+    function transformUnion(typs: any[], val: any): any {
+        // val must validate against one typ in typs
+        const l = typs.length;
+        for (let i = 0; i < l; i++) {
+            const typ = typs[i];
+            try {
+                return transform(val, typ, getProps);
+            } catch (_) {}
+        }
+        return invalidValue(typs, val, key, parent);
+    }
+
+    function transformEnum(cases: string[], val: any): any {
+        if (cases.indexOf(val) !== -1) return val;
+        return invalidValue(cases.map(a => { return l(a); }), val, key, parent);
+    }
+
+    function transformArray(typ: any, val: any): any {
+        // val must be an array with no invalid elements
+        if (!Array.isArray(val)) return invalidValue(l("array"), val, key, parent);
+        return val.map(el => transform(el, typ, getProps));
+    }
+
+    function transformDate(val: any): any {
+        if (val === null) {
+            return null;
+        }
+        const d = new Date(val);
+        if (isNaN(d.valueOf())) {
+            return invalidValue(l("Date"), val, key, parent);
+        }
+        return d;
+    }
+
+    function transformObject(props: { [k: string]: any }, additional: any, val: any): any {
+        if (val === null || typeof val !== "object" || Array.isArray(val)) {
+            return invalidValue(l(ref || "object"), val, key, parent);
+        }
+        const result: any = {};
+        Object.getOwnPropertyNames(props).forEach(key => {
+            const prop = props[key];
+            const v = Object.prototype.hasOwnProperty.call(val, key) ? val[key] : undefined;
+            result[prop.key] = transform(v, prop.typ, getProps, key, ref);
+        });
+        Object.getOwnPropertyNames(val).forEach(key => {
+            if (!Object.prototype.hasOwnProperty.call(props, key)) {
+                result[key] = transform(val[key], additional, getProps, key, ref);
+            }
+        });
+        return result;
+    }
+
+    if (typ === "any") return val;
+    if (typ === null) {
+        if (val === null) return val;
+        return invalidValue(typ, val, key, parent);
+    }
+    if (typ === false) return invalidValue(typ, val, key, parent);
+    let ref: any = undefined;
+    while (typeof typ === "object" && typ.ref !== undefined) {
+        ref = typ.ref;
+        typ = typeMap[typ.ref];
+    }
+    if (Array.isArray(typ)) return transformEnum(typ, val);
+    if (typeof typ === "object") {
+        return typ.hasOwnProperty("unionMembers") ? transformUnion(typ.unionMembers, val)
+            : typ.hasOwnProperty("arrayItems")    ? transformArray(typ.arrayItems, val)
+            : typ.hasOwnProperty("props")         ? transformObject(getProps(typ), typ.additional, val)
+            : invalidValue(typ, val, key, parent);
+    }
+    // Numbers can be parsed by Date but shouldn't be.
+    if (typ === Date && typeof val !== "number") return transformDate(val);
+    return transformPrimitive(typ, val);
+}
+
+function cast<T>(val: any, typ: any): T {
+    return transform(val, typ, jsonToJSProps);
+}
+
+function uncast<T>(val: T, typ: any): any {
+    return transform(val, typ, jsToJSONProps);
+}
+
+function l(typ: any) {
+    return { literal: typ };
+}
+
+function a(typ: any) {
+    return { arrayItems: typ };
+}
+
+function u(...typs: any[]) {
+    return { unionMembers: typs };
+}
+
+function o(props: any[], additional: any) {
+    return { props, additional };
+}
+
+function m(additional: any) {
+    const props: any[] = [];
+    return { props, additional };
+}
+
+function r(name: string) {
+    return { ref: name };
+}
+
+const typeMap: any = {
+    "TopLevel": o([
+        { json: "external_order_ref", js: "external_order_ref", typ: u(undefined, "") },
+        { json: "info", js: "info", typ: r("OrderCustomer") },
+    ], "any"),
+    "OrderCustomer": o([
+        { json: "country", js: "country", typ: u(undefined, "") },
+        { json: "email", js: "email", typ: u(undefined, "") },
+        { json: "first_name", js: "first_name", typ: u(undefined, "") },
+        { json: "last_name", js: "last_name", typ: u(undefined, "") },
+        { json: "newsletter", js: "newsletter", typ: u(undefined, "") },
+        { json: "order_number", js: "order_number", typ: "" },
+        { json: "phone", js: "phone", typ: u(undefined, "") },
+        { json: "post_code", js: "post_code", typ: u(undefined, "") },
+        { json: "type", js: "type", typ: u(undefined, "") },
+    ], "any"),
+};