diff --git a/src/maintenance-pool/dto/create-pool.dto.ts b/src/maintenance-pool/dto/create-pool.dto.ts
index 3509257..e009854 100644
--- a/src/maintenance-pool/dto/create-pool.dto.ts
+++ b/src/maintenance-pool/dto/create-pool.dto.ts
@@ -28,10 +28,9 @@ export class CreatePoolDto {
   @IsUUID()
   repositoryId?: string;
 
-  @ApiProperty({ required: false })
-  @IsOptional()
+  @ApiProperty()
   @IsUUID()
-  createdById?: string;
+  createdById: string;
 
   /** The sponsor's standing recurring commitment; deposits never overwrite it (#93). */
   @ApiProperty({ required: false })
diff --git a/src/milestones/dto/create-milestone.dto.ts b/src/milestones/dto/create-milestone.dto.ts
index 390ae26..f3549c0 100644
--- a/src/milestones/dto/create-milestone.dto.ts
+++ b/src/milestones/dto/create-milestone.dto.ts
@@ -20,10 +20,9 @@ export class CreateMilestoneDto {
   @IsUUID()
   repositoryId: string;
 
-  @ApiProperty({ required: false })
-  @IsOptional()
+  @ApiProperty()
   @IsUUID()
-  sponsorId?: string;
+  sponsorId: string;
 
   @ApiProperty({ maxLength: 200 })
   @Transform(({ value }: { value: unknown }) =>
diff --git a/src/teams/dto/create-team.dto.ts b/src/teams/dto/create-team.dto.ts
index e5487c2..ef81e3d 100644
--- a/src/teams/dto/create-team.dto.ts
+++ b/src/teams/dto/create-team.dto.ts
@@ -49,10 +49,9 @@ export class CreateTeamDto {
   @MaxLength(100)
   name: string;
 
-  @ApiProperty({ required: false })
-  @IsOptional()
+  @ApiProperty()
   @IsUUID()
-  createdById?: string;
+  createdById: string;
 
   @ApiProperty({ type: [TeamMemberSplitDto] })
   @ArrayMinSize(1)