I'm a "Fixer"

Agree completely.

The issue here is that your child is an adult. Not only is this her issue to sort out, but having a parent get involved in someone's professional life is very unprofessional. (Case in point - a colleague of mine had a nursing student who had a problem being on time. The student's MOTHER told my colleague that these were "children" and that if they needed help getting up in the morning, that should be provided.)

If your AD has an issue with a customer, and you hear about it, the appropriate response is to advise the customer to deal with your AD directly.

Yes Blinko is right put them in touch then leave them to it. Don't get involved in business with friends and family unless you are part of said business, it can lead to trouble all round.

Just give your friends you DDs contact number and let them sort things themselves,when you are a mum you can't do right for doing wrong sometimes.
Let you DD get on with her own business unless she is giving you a %

Best to wait to be asked to ‘fix’, frustrating though it may be at times. Try to give your friends a message that your daughters business is hers alone and any contact must be direct. Sometimes it’s best just not to know.

A wide berth all round.

I think you made a mistake involving friends with your daughters business you should of said sorry but no.
You should now keep out of it I’m afraid.

Don't become piggy in the middle. Put your friends directly in touch with your daughter and vice versa. Then stay out of it.