S.L.
Maybe what you can do next time your daughter asks for a playdate is have a talk with her about it. You said friends as in plural right? Maybe next time just invite one friend over and see how that goes? Ask her if her friend come over, will she be ready to play with her or maybe make a list of activities with her that they can play and tell her when her friend arrives that she can add to the list too. Ask her WHAT she wants to do with her friend before she comes over.
I'm sure you will get great advice about this but that's just one thought =-)