Some clans have more mages than just the Keeper and the First. Merrill's original clan had a surfeit of mages and that is why she was given to Marethari as the clan did not have any mage children of their own. Lanya says she was not the only one considered for First, so that would suggest other mages in that clan, even though we never saw them.
I await with interest what a Dalish would be doing at the Peace Conference. The Dalish have never considered themselves under Chantry jurisdiction so it is hard to see why they would respond to a request for a representative, when I was under the impression it was called to resolve the Mage/Templar problem. Nor would they be likely to be there simply as pilgrims. This would suggest that the Inquisitor was there as an independent person, perhaps sent by the clan in the vicinity to find out what was going on and whether it was likely to pose a threat to them.
Once the companions have been fully revealed, I do hope we are given some background on this. If I must be a Dalish elf, I would like to know why.