custom control for TFS work item type

I will explain my question with an example. Lets consider TFS "Bug" work item type. In the bug work item type there is a "Developer" and "Tester" dropdown. Using the inbuilt rule types we can only assign "VALIDUSER" to each drop down. This displays all the windows user in the drop down. I want to be able to create a custom subteam under "TeamMembers" node and assign members to the sub team. For example as shown in the below snapshot:

alt text http://www.imagechicken.com/uploads/1267041开发者_C百科644094323600.png

The "Developer" drop down should display users from the new "Developer" subteam and not all the VALIDUSER. Similarly "Tester" drop down should display users from the new "Tester" subteam.

alt text http://www.imagechicken.com/uploads/1267042457029195500.png

I am thinking of creating a custom work item control and then call the TFS API to fetch the custom subteam members.

If anyone has worked on this before or have any better (and simple :)) ideas to achieve the above please suggest.

Update

I just created a custom work item control and called TFS API to get the list of members in the custom group. So this is done. But I would still like to know if there is a better way to achieve same results.

Well..There is a better way to do the same.. Thanks to Marcel !!

how-to-assign-a-work-item-to-a-group-and-actually-have-it-show-a-list-of-values