You say in http://www.flyertalk.com/forum/star-...asia-base.html that your primary carrier will be SQ.. You should really have just made one thread on this topic.

I would rate SQ>CX>MH>UA/AA.

Your FFP and carrier choice do not need to be the same. You can credit OW flights to other OW FF programs. However, some additional status benefits apply only for that airline. AA SWU's are for AA metal only for example.

You can create a FF account for each member of your family, and they can earn miles to their account. You may want to look for a program that allows you to pool/transfer miles.