diff --git a/src/models/GroupContact.ts b/src/models/GroupContact.ts
index e243d00..3ed4e63 100644
--- a/src/models/GroupContact.ts
+++ b/src/models/GroupContact.ts
@@ -1,8 +1,15 @@
-import { Entity } from "typeorm";
+import { Entity, OneToMany } from "typeorm";
 import { Participant } from "./Participant";
+import { RunnerGroup } from "./RunnerGroup";
 
 /**
  * Defines a group's contact.
 */
 @Entity()
-export class GroupContact extends Participant{}
\ No newline at end of file
+export class GroupContact extends Participant{
+  /**
+    * Used to link runners to donations.
+    */
+  @OneToMany(() => RunnerGroup, group => group.contact)
+  groups: RunnerGroup[];
+}
\ No newline at end of file
diff --git a/src/models/RunnerGroup.ts b/src/models/RunnerGroup.ts
index d619e2f..c35ad48 100644
--- a/src/models/RunnerGroup.ts
+++ b/src/models/RunnerGroup.ts
@@ -1,4 +1,4 @@
-import { PrimaryGeneratedColumn, Column, OneToMany } from "typeorm";
+import { PrimaryGeneratedColumn, Column, OneToMany, ManyToOne } from "typeorm";
 import {
   IsInt,
   IsNotEmpty,
@@ -34,7 +34,7 @@ export abstract class RunnerGroup {
    */
   @Column()
   @IsOptional()
-  //TODO: Relationship
+  @ManyToOne(() => GroupContact, contact => contact.groups)
   contact?: GroupContact;
 
   /**