It isn’t the full fams’ fault that the other fams didn’t fill up. They shouldn’t necessarily be inconvenienced because others didn’t draft or random in at the same pace. Keep in mind also that merging the families is already itself a compromise.
We have to keep things moving. Taking your suggestion to the extreme, we would only start the round once all families fill up, which will cause some of those that have joined already to go inactive.
Everybody’s vote here is useful. We’ll make a final decision 6 hours before current SoR.