If you're collecting miles solely on KrisFlyer and don't travel on a regular basis then there's little sense in splitting up accruals across multiple FFPs, otherwise accruing enough to redeem before the miles expire could become an issue. Plus achieving status becomes that much harder when the miles don't all fall into one account.

If you do travel regularly though and also do a lot of family flights then maybe Miles & More is worth a look? Good family mileage pooling scheme and possibly more miles credited on the flight(s) you mentioned.