"A minor hassle is that I like to be even handed with them , so...

"A minor hassle is that I like to be even handed with them , so sorting out how to do that with one having a different balance and contributions,"
There is no problem with this. The personal balances are all kept separate in the SMSF, however profits and losses are distributed as per the percentage of each balance of the member in the fund. I have managed to double the balances of my children by actively targeting capital gains trading shares. We still continue to hold property in one fund but have mostly exited as the returns on the share market are considerably more.
There is only upside in the arrangement, you can also make an after tax contribution to your children's fund if you're having a good year and you don't wish to takeout your entire minimum pension in that year.
This way Shorten's franking credit rip-off will never affect the fund as the franking credits will always be used.
The lefties will be crying when they find out how little they will be able to rip-off from hard working Aussies.