I would do a water change first (as you won't be able to once you've started treating), then start the treatment. Do the full course, when it's finished do a water change and run carbon in the filter for 3 or 4 days to remove it. Hopefully it'll sort them out
I don't really have much input apart from 'good luck!' haha!
Would the mums round up their young and dart into a shell if you put your hand or a net in or anything? If she does them would it be possible to net the whole shell and move it across? Then mum and babies stay together? Or am I being silly with my nil experience of cichlids!