For anyone interested, I always thought the maximum number of Infiltrators that could be obtained from the Pitt was 4 - but I've managed to get 7 of them.

What I did:

- Side with Wernher and take the baby. All raiders are now hostile.

- At some point while the raiders are still hostile, exit Downtown to the Bridge area and shoot the Infiltrators from the Raiders' hands. Don't kill them!

- Take the baby to Wernher, then tell him you have second thoughts. Deal with Wernher.

- Take the baby back to Ashur. All raiders *except* the three in the bridge area will now be marked as friendly again.

I'm not 100% sure when (it's possible) to exit Downtown and obtain the Infiltrators, it's either before taking the baby to Wernher or just after dealing with Wernher.

Once you've returned the baby to Ashur and sided with him, completing the DLC - the raiders in the bridge area will still be hostile. But at some point, their Infiltrators respawned for me.

I've still kept them alive, but it hasn't happened again for me. I think it only happens once, maybe they sort of reset after the DLC?

Maybe someone who knows how to use the GECK can figure this out...

Edit:

- Gruber in the Arena has 1 Infiltrator

- Mex and the two other Raiders in the Bridge/Gate to Downtown are all have Infiltrators = 3

- Mex and the other Raiders Infiltrators respawn = 3

- Total of 7 Infiltrators