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?

Thank you!