Apologies for the vague title, and I'm probably posting this in the wrong place. If so, please point me in the right direction.

Long story short, me (Male, 25) and my boyfriend (male, 29) have happily been together for 2 years last November (2014). He's bi-sexual, and I'm gay. We're in a semi-open relationship where we can fool around with our close friends as long as we both trust the third party (on either side) and we both have someone to play with (IE: If he goes with a girl, I go with a guy).

This part isn't the issue. My boyfriend who likes girls too has been missing out on girl fun time and has been browsing chat apps and websites looking for suitable candidates. All potentially interested parties know fully about our relationship, that he's in a relationship with me, and is just interested in the 'friends with benefits' role.

The downsides lie in the fact that my boyfriend often has bad reactions with using condoms. He'd be happy using them if it weren't for the reactions. We both have unprotected sex with each other regularly, but if it involves someone else, we get STI/STD tested beforehand, and around 1 month after.

My boyfriend doesn't want to risk getting any kind of infection, or worse, conceiving a child should he choose not to use protection for his fun times. So I ask you as a community:

Is it morally wrong to ask the new playmate to sign an agreement to remove liability should conception happen, and accept liability should an infection happen?

What would your initial reactions be if this topic came up after knowing the person for a month or two, and casually chatting in a bar?

The system itself would be a page explaining that she (the play mate) signed the document knowing she was free of sexual infections and had been tested within the last month, and that she accepts responsibility of actions should conception happen.

I know it sounds really bad, but with both of us as unemployed students, we really can't afford to support a child, and having one enter our lives would destroy my relationship with him.

Edit: All parties are natural born UK Citizens, and as such only UK law will apply in this situation.

Edit: My boyfriend does want to father a child at some point in the future, just not right this second when finances aren't the best.

TL;DR Is it morally wrong to ask the new playmate to sign an agreement to remove liability should conception happen, and accept liability should an infection happen?