It will also be more complex to take into account all the AR1 possible endings. There are 12 endings! More work, and more risk of bug.
HanakoXVN stat that there isn't ONE cannon ending, but any ending with at least one of the Fujikawa sisters leads to AR2.
Valerie is adopted (like Spoon, but he was adopted first! :-)). One of her legal mom is Violet. The other seems to be the Fujikawa sisters Violet ended with in AR1.
Valerie call all the other girls (Violet may have ended with too) as her moms (she said she may have too many moms :-)), but Violet and the Fujikawa girl are her legal moms.
The only question remaining is what with the Legend Ending where Violet ended with the two Fujikawa sisters. I have the feeling the second legal mom will be Rikako, but it's just my 2 cents.
Anyway, HanakoXVN has explain that the exact number of Valerie moms will never be specified in AR2. And I think the only one Valerie will have contact (and we may see) will be Violet.
Thus, any ending from AR1 with one of the Fujikawa sisters will work.