How to do a reverse-rollover? Especially the after-tax part

[Taxger]

Hi there,

I want to do a reverse-rollover, meaning transferring my IRA balance to my company's 401k.

However, this reverse-rollover can only do the pre-tax part.

Can I just move the after-tax part to my own Roth IRA?

Will this 1) cause me to file additional tax 2) or impact my contribution on this year's backdoor IRA? 3) I guess it doesn't matter on how many times I do the reverse-rollover or the order of moving to company's 401K or my roth IRA, right?

Thank you!