I agree with Merge having the better software. Most everyone will agree with that. Merge has what I consider to be the best client software. However, their payout policies have sucked since Black Friday.
For most of us, the change to WPN by BCP was a godsend. We understood that the financials from Merge would not slide right over to the financials for WPN.
Every site has some form of KYC (Know Your Customer). There could be a Universal Way, except the UIGEA squashed what was close to being that Universal Way. That was 8 years ago, and I have even forgot what that company's name was. Someone will provide it shortly. They still exist, just not in the USA.
So buckle up, provide the fresh info any site that has your money wants, and get on with it. You will most likely only have to do it once.
FWIW, it is likely that ACR and BCP might each want the same info, but even though they are on the same network, you might have to provide it to each.