"have you been a surrogate, or used one, to know that it's wrong to expect a relationship with each other?"
No. Nor have I been in a plane crash but I think that they're bad too.
I have, however, acted in a consultative capacity for the HFEA and have been instrumental in the decisions around legislation and guidance relating to spe donors and contact with their offspring. I also at one point considered using donor eggs myself but didn't have to go down that path.
And I absolutely stand by what I say: I cannot imagine many worse situations where a couple affected by fertility issues are so vulnerable to an eternity of emotional blackmail.
Good for you that you have a good relationship with your receipients. I wonder how easy it would be for them to break it off with you if they wanted?
If you're able, and the recipients are willing too, to have a friendship, then fair enough, but that absolutely SHOULDN'T be a motivating factor, as it certainly was in Shannon's case.