I've seen a great provider several times recently whom I tip $100 over the usual $150.  She is bringing a friend to our next visit which will be $200 total.  My question is, do I still tip my provider the usual $100, which I'd like to do?  And, do I tip her friend an equal amount, or do I tip the friend based on my experience.

If you stop tipping your regular girl, she may feel insulted. As far as the other girl goes, that is up to you. If possible, have the donations is differet envelopes which each girls name on them. This should keep things hush hush. It is ultimately your choice. Good luck.