How do you give in honor/memory of someone but acknowledge someone else?
It depends a bit on the purpose of gathering soft credits and acknowledging the donation. For acknowledgement purposes it may be sufficient to gather email and name (and perhaps address) on a front or backend form and with a hook send off an acknowledgement email. I think this can be very nice for those related to the honoured person, allowing them to send a thank you card if they want. Personally I won't bother creating additional soft credits for the mother and uncle beyond those for the person in honour/memory of.