Porting just ONE of my 5 ATT numbers to Google Voice and Concern of Account Issues

I just ported my old landline number to my ATT account so now I have a total of 5 mobile numbers. (4 previous mobile numbers I've had for years and this new one.)

Now I would like to port this old landline number (that is now on ATT and part of my 5 lines) over to Google Voice just to park the number. I do NOT want to disrupt my other 4 mobile numbers I have with my ATT account. I only want to port this ONE number from my ATT account to Google Voice and leave the rest as-is.

When I went to port / transfer my old landline number (now an ATT number) from ATT into Google Voice, I saw a generic warning message from the Google Voice system:

"Your mobile phone service plan will be terminated when you port your number to Google Voice and your carrier may charge you an early termination fee."

Taken literally, that is a scary message! I want to keep my 4 mobile numbers. I ONLY want to move that one number that used to be my old landline.

Can someone confirm to me that when I port a SINGLE number from my multi-number account it won't close, or mess with in any way, my existing other 4 numbers and relationship with ATT?

Much appreciated,

MHC