We have related builds that should not be run in parallel (say A1, A2, A3), while unrelated builds (D, E, F) can be run in parallel with A1, A2, A3.

Our only options seem to be:

1) Define only one agent, and have all builds queue up to run (D, E, F have to wait for A1 to finish)
2) Define multiple agents, but be unable to prevent certain builds from running in parallel (A1, A2 may run in parallel if triggered at around the same time).

Is there are way to build a configuration like this with the current feature set?