BE ADVISED! VIDA detects any module replacement or addition!

[IMAY2023]

If I revert to VIDA’s original config, I receive errors. I was told that VIDA will stop updates if it detects errors and differences between the config and the actual equipment.

Not true. If only VIDA recognises added ECUs.  
First revert the car to OEM config.  You mentioned that the previous owner replaced the manual seats with the electric. Under the seat you have the seat controller. Just disconnect the power connector from it. while keeping all other (air bag, occupant detection sensor, ..)  connected. Disconnect the power to the WAM too.   So that VIDA does not detect those modules at all. 

You will get CCM DTCs "added heating seat modules" but VIDA does not care about them at all. If you want to avoid it too, just disconnect the power. Most likely the previous owner used a fuse tab under the glove box.

[Kokksya]

thx, i will try
oh, i remember, that bliss is retrofit too, is there any problem?

[IMAY2023]

Well, VIDA will certainly detect and show the added BLISS under HW changes because they are on the CAN BUS with WAM.  Then it will block the total upgrade. 
You have two options. 
1) Try to order BLISS (whatever showing up under HW changes) and install. 
This is risky because after you purchase it and try to install, VIDA might not install it at all giving an error message "This software does not fit to your VIN"  VIDA will not warn you that this software does not fit before hand!  You may ask for refund from the VOLVO bookstore because of ordering wrong software. 
If it does not install, you will need to disconnect the BLISS modules and then order and install configuration change software to clear out previously detected HW changes. 
Once a HW change is detected is stays there forever regardless if the original equipment is installed or added module is removed before a new read out is performed even from a different VIDA or account until configuration test is order and installed to verify indeed the replaced or added module is removed. 

2) Disconnect BLISS modules from their connectors before connecting VIDA to the car!