Everyone here can test it for themselves easily enough.

I presume you need to first add another user to your PP business account. You can do this as follows:

1) Login to PP
2) Click the icon of the silhouette of a human head in the top right corner right next to the "Logout" button
3) Click "Profile & Settings"
4) On the new page that opens in the left hand menu click "My settings"
5) In the new pane that opens on the right you'll see a "Manage Users" row, click "get started". Here you can essentially add an authorized user to your account.

I have no desire to use this method so I don't care to test my theory, but I presume you can add a user who has a business account and a PPBDMC here and then you may be able to add their PPBDMC as a backup funding source to your PP account. It's certainly within the realm of possibilities.

All you need to succeed in this arena is an inquisitive mind and the will to try things, even if they fail.

So if you want, give that a shot and then feel free to report back here if it works. That is the point of this forum. Of course, it could be an elaborate hoax, and shame on them if that's the case, but it may not be.