What to do?

[SheilaJoy]

You've gotten great advice. I just wanted to add that it's not that big of a deal to set the baby down in a safe place and let her cry for just a few minutes. I'm not saying for an extended period of time, but we all need to do this now and then to regain our sanity.
ditto with the sposie idea, and asking the mom what she wants you to do with baby when you need to get other things done around the house. If she says just put her in the bouncer, then just put her in the bouncer.