I am RME user as you. I could test it only with my UFX+, thats all I mean. The last mile you have to go.
But where is the risk nowadays ? If you buy online you can send it back 14-30 days later without any money loss, depending on the dealer.
At the end this solution boils down to the only technical requirement to connect a digital source to the ADI-2 Pro / AE / DAC and that you route your Audio through that digital source. The rest you switch on the ADI-2 Pro / AE / DAC as you can see from the picture on the right hand side.
If you want to integrate an ARC USB on top, to be able to control even more, then it has to be a RME recording device which supports TotalMix FX. RME updated the drivers of all of their recording interfaces back to (I think it was) ~2002. So you have maby RME recording interfaces where you can use the ARC USB.
If you look to the product page on RME web server then you see what digital sources are supported by the three different devices. ADI-2 Pro and AE are equal in terms on I/O, only the DAC is slightly different as its missing the typical studio standards like AES. Therefore I updated the picture (v2 now) to make it clear, what each of these 3 devices support in terms of digital inputs.
All that YOU need to perform at the end is to route your audio signals through the ADAT output of your recording interface.
Best is maybe that you assign in TotalMix FX "ADAT 1/2" to be your "Main Out" as this will be now your "Main Out". Maybe you need to adjust on the ADI from what digital source the signal arrives, but "Auto" should do as you can see in the configuration sniplet in the drawing, because Auto means automatic detection.
You won't get a written statement from me that it 100% works, because I do not own your equipment (BBFP).
But if you look at it, if this works i.e. with an UFX+ ... Why should it not work with a BBFP ?!?!?!
Either I did a mistake or you do not understand the setup
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14