Must the missed Dawn prayers that were not performed be made up, due to ignorance of the ruling regarding the obligation to make them up upon waking, along with not remembering their number?

Fajr prayer is not to be combined with any other prayer, by consensus. If someone misses the Fajr prayer due to sleep or forgetfulness, they must make it up immediately upon waking or remembering. It is obligatory to promptly make up any missed prayers that were due to a valid excuse. As for someone who intentionally neglected it, the majority of scholars hold that making it up is still obligatory, and this is the chosen and more cautious opinion.