diff --git a/src/models/Donor.ts b/src/models/Donor.ts
index 0ed60da..5d0af07 100644
--- a/src/models/Donor.ts
+++ b/src/models/Donor.ts
@@ -9,9 +9,9 @@ import { Participant } from "./Participant";
 export class Donor extends Participant {
   /**
    * Does this donor need a receipt?.
-   * Default: True
+   * Default: false
    */
   @Column()
   @IsBoolean()
-  receiptNeeded = false;
+  receiptNeeded: boolean = false;
 }
\ No newline at end of file
diff --git a/src/models/GroupContact.ts b/src/models/GroupContact.ts
index 3ed4e63..58a07a7 100644
--- a/src/models/GroupContact.ts
+++ b/src/models/GroupContact.ts
@@ -1,12 +1,86 @@
-import { Entity, OneToMany } from "typeorm";
-import { Participant } from "./Participant";
+import { PrimaryGeneratedColumn, Column, OneToMany, ManyToOne, Entity } from "typeorm";
+import {
+  IsEmail,
+  IsInt,
+  IsNotEmpty,
+  IsOptional,
+  IsPhoneNumber,
+  IsString,
+} from "class-validator";
+import { Address } from "./Address";
+import { Donation } from "./Donation";
 import { RunnerGroup } from "./RunnerGroup";
 
 /**
  * Defines a group's contact.
 */
 @Entity()
-export class GroupContact extends Participant{
+export class GroupContact {
+    /**
+   * Autogenerated unique id (primary key).
+   */
+  @PrimaryGeneratedColumn()
+  @IsOptional()
+  @IsInt()
+  id: number;
+
+  /**
+   * The contact's first name.
+   */
+  @Column()
+  @IsNotEmpty()
+  @IsString()
+  firstname: string;
+
+  /**
+   * The contact's middle name.
+   * Optional
+   */
+  @Column()
+  @IsOptional()
+  @IsString()
+  middlename?: string;
+
+  /**
+   * The contact's last name.
+   */
+  @Column()
+  @IsOptional()
+  @IsString()
+  lastname: string;
+
+  /**
+   * The contact's address.
+   * Optional
+   */
+  @IsOptional()
+  @ManyToOne(() => Address, address => address.participants)
+  address?: Address;
+
+  /**
+   * The contact's phone number.
+   * Optional
+   */
+  @Column()
+  @IsOptional()
+  @IsPhoneNumber("DE")
+  phone?: string;
+
+  /**
+   * The contact's email address.
+   * Optional
+   */
+  @Column()
+  @IsOptional()
+  @IsEmail()
+  email?: string;
+
+  /**
+   * Used to link the contact as the donor of a donation.
+   */
+  @OneToMany(() => Donation, donation => donation.donor)
+  donations: Donation[];
+
   /**
     * Used to link runners to donations.
     */
diff --git a/src/models/RunnerCard.ts b/src/models/RunnerCard.ts
index e751506..f978d0c 100644
--- a/src/models/RunnerCard.ts
+++ b/src/models/RunnerCard.ts
@@ -42,10 +42,11 @@ export class RunnerCard {
 
   /**
    * Is the card enabled (for fraud reasons)?
+   * Default: true
    */
   @Column()
   @IsBoolean()
-  enabled = true;
+  enabled: boolean = true;
 
   /**
    * Used to link cards to a track scans.
diff --git a/src/models/RunnerGroup.ts b/src/models/RunnerGroup.ts
index 52f478f..a7c199b 100644
--- a/src/models/RunnerGroup.ts
+++ b/src/models/RunnerGroup.ts
@@ -43,10 +43,4 @@ export abstract class RunnerGroup {
    */
   @OneToMany(() => Runner, runner => runner.group)
   runners: Runner[];
-
-  /**
-   * Used to link teams to runner groups.
-   */
-  @OneToMany(() => RunnerTeam, team => team.parentGroup)
-  teams: RunnerTeam[];
 }
\ No newline at end of file
diff --git a/src/models/RunnerOrganisation.ts b/src/models/RunnerOrganisation.ts
index 22fe8a5..958b363 100644
--- a/src/models/RunnerOrganisation.ts
+++ b/src/models/RunnerOrganisation.ts
@@ -1,7 +1,8 @@
-import { Entity, Column, ManyToOne } from "typeorm";
+import { Entity, Column, ManyToOne, OneToMany } from "typeorm";
 import { IsOptional,} from "class-validator";
 import { RunnerGroup } from "./RunnerGroup";
 import { Address } from "./Address";
+import { RunnerTeam } from "./RunnerTeam";
 
 /**
  * Defines a runner organisation (business or school for example).
@@ -16,4 +17,10 @@ export class RunnerOrganisation extends RunnerGroup {
   @IsOptional()
   @ManyToOne(() => Address, address => address.groups)
   address?: Address;
+
+    /**
+   * Used to link teams to runner groups.
+   */
+  @OneToMany(() => RunnerTeam, team => team.parentGroup)
+  teams: RunnerTeam[];
 }
\ No newline at end of file
diff --git a/src/models/RunnerTeam.ts b/src/models/RunnerTeam.ts
index e716e27..f12c5eb 100644
--- a/src/models/RunnerTeam.ts
+++ b/src/models/RunnerTeam.ts
@@ -1,6 +1,7 @@
 import { Entity, Column, ManyToOne } from "typeorm";
 import { IsNotEmpty } from "class-validator";
 import { RunnerGroup } from "./RunnerGroup";
+import { RunnerOrganisation } from "./RunnerOrganisation";
 
 /**
  * Defines a runner team (class or deparment for example).
@@ -13,6 +14,6 @@ export class RunnerTeam extends RunnerGroup {
    * Optional
    */
   @IsNotEmpty()
-  @ManyToOne(() => RunnerGroup, group => group.teams)
-  parentGroup?: RunnerGroup;
+  @ManyToOne(() => RunnerOrganisation, org => org.teams)
+  parentGroup?: RunnerOrganisation;
 }
\ No newline at end of file
diff --git a/src/models/Scan.ts b/src/models/Scan.ts
index 6c2dccc..055e94b 100644
--- a/src/models/Scan.ts
+++ b/src/models/Scan.ts
@@ -37,8 +37,9 @@ export abstract class Scan {
 
     /**
    * Is the scan valid (for fraud reasons).
+   * Default: true
    */
   @Column()
   @IsBoolean()
-  valid = true;
+  valid: boolean = true;
 }
diff --git a/src/models/ScanStation.ts b/src/models/ScanStation.ts
index c89a3a4..4415ebc 100644
--- a/src/models/ScanStation.ts
+++ b/src/models/ScanStation.ts
@@ -47,10 +47,11 @@ export class ScanStation {
 
   /**
    * Is the station enabled (for fraud reasons)?
+   * Default: true
    */
   @Column()
   @IsBoolean()
-  enabled = true;
+  enabled: boolean = true;
 
   /**
    * Used to link track scans to a scan station.