Using hot batch to re-distill heads and tails

[rednose]

I'm about to finish a whisky run.

May I use the hot batch to add heads and tails from previous runs?

My thought is to use the left over flavor for the re-distill instead of just plain water.

Do I have to wait that the batch gets colder for example 60 C before adding the faints?

I'm planning to go to max 20% ABV of the batch or should I go higher?

Thanks in advance

Joe