Thankyou so much for taking the time to post a response.Counselling seems to be the no.1 piece of advise and was probably the one direction that my SIL and i hadn't focussed on.I guess the fact that the three of us are all very positive meant that we perhaps felt ready and prepared to deal with any issues both before and after conception, on our own .... AND that is why i posted my original message ... genuine feedback! It's the unknown questions and issues that we may not have even thought of that we perhaps need to address.I have just phoned my SIL and told her to check out your response ... invauable words , thanks again and i will keep you updated.
Gary,

Firstly you are doing an absolutely brilliant thing - well done you!

Secondly having briefly been down this path (my BIL offered to be our donor but then withdrew because he had difficulty with the issues involved) I would suggest a number of things:

1) talk to a counsellor to make absolutely sure that this is the path you want to follow. Preferably use a counsellor that has a background in AC issues so that he/she will be able to discuss things with you that you may not have previously thought of.

2) talk to a lawyer and ensure you have thought about the legal ramifications

3) think about the long term issues. Will you be as comfortable if your SIL finds a partner with whom she will raise her child?

4) Finally make sure that you always talk through any issue. We do this all the time with our current known SD. Remember that this will be at the very least 18 years of negotiation and communication.