Child outside of marriage

I have a situation: One of my friends had a child outside of marriage. Wife (with SWV) got pregnant by a friend and his husband (dependant) is weirdly okay with it. The baby is to be born in a few months, and they are planning to put the baby daddy's name in the certificate or leave it blank as terms from the husband. Now the question is: what will happen when applying for a visa for the child? Will the home office question this? Has anyone ever found themselves in such a situation?