So there is a major flaw in the MR Handy AI that causes alot of problems. The issue is the fact that when a mr handy returns from the wasteland you cannot send it back into the wasteland after collecting the caps. This becomes a major issue when you have more handys than floors in your vault. this needs to be fixed ASAP since survivors can be sent back into the wasteland without needing to re enter the vault and when al floors are occupied with handies this results in you needing to play a game of rotation which can sometimes result in 5-6 cycles of the vault door and trigger multiple consecutive deathclaw attacks.

Frankly the main issue may actually relate to how the vault door cycles. Perhaps when your sending or retreiving multiple characters to and from the wasteland you should have the option to manually open and close the door so that you can deal with groups without having to cycle the door more than once. in fact the whole automated vault door thing is rather stupid it should be a manual control especially when you have groups of 10 or more surviors heading out at a time.

for the most part with survivors you can time the door properly to allow groups to return with only one door cycle however with the limitation of one mr handy per floor this cannot be acomplished

I had posted a suggestion earlier about adding a Robotics Lab room that acts as a repair center for mr handies as well as a Storage space that allows you to store additional Offline handies when you do not have enough floors