I agree that chins do have memory (which is why it's best not to reintroduce ever after a near deadly fight), but also that just because they are family doesn't mean they will get along. If you think about it, how would you like to get out on your own then have your mother/sister/brother/father move in with you, some people would love it, others hate it. Also even bonded pairs, who have never been separate in their lives can one day decide, for no obvious reason, that they don't want to be housed together anymore too.
Another thing to point out is your cage size, 2'x2'x2' is the bare minimum required for one chin (some people say 2'x2'x3' but 8 cubic ft per chin is legal minimum in Canada anyway). Adding a couple more feet to the top will help, but there is no such thing as too much space for chins so if you can go bigger go bigger. The more space you give them, especially when you have more then one, the more room they have to get away from each other. If they can't have alone time that can cause a fight. You will also want to wash down the whole cage you are planing to put both in so the area is neutral smelling as possible. Rearrange the cage too would help so it looks different.
If your plan/hope was to just throw them in the same cage together, that will not work. You will need to quarantine (separate cage and separate room) the mother for 30 days, as said they have been separate and the mother could have been exposed to illness. It also gives you time to get to know her and for her to get to know you and settle in. After quarantine it's best to just approach it like introducing a new chin, the fact that they are mother and daughter might help make it go faster, or might not help at all.