What happens if you don't collect Hero Merit?

I recently got Nowi to the 1000 Hero Merit (HM) mark, which causes feathers to spring from her on the Home screen, earning me another 500 feathers if I click on Nowi!

I was wondering, if I don't click and don't collect these 500 bonus feathers, what will happen when I reach 1500 HM on Nowi?

Will I gain 1000 feathers?
Will i get two prompts to gain 500 each and not lose anything?
Will I only get a single prompt to get the 500 feathers, effectively losing 500 in the process?

There doesn't seem to be a reason to not collect the 500 feathers now, but I was wondering how this interaction would play out.

Solution 1:

After painstakingly allowing Joshua to grind out 500 more HM without accepting his previous gift, I can answer this.

You just get all of the accrued HM feathers at the same time.