In my piece yesterday, I pointed out that I was in the room when the plan for WINEP was first drawn up. I was working at AIPAC and it was Steve Rosen who cleverly came up with the idea for an AIPAC controlled think-tank that would put forth the AIPAC line but in a way that would disguise its connections.
There was no question that WINEP was to be AIPAC's cutout. It was funded by AIPAC donors, staffed by AIPAC employees, and located one door away, down the hall, from AIPAC Headquarters (no more. It has its own digs). It would also hire all kinds of people not identified with Israel as a cover and would encourage them to write whatever they liked on matters not related to Israel. "Say what you want on Morocco, kid." But on Israel, never deviate more than a degree or two.
WINEP was created initially at a time when AIPAC was in financial trouble and having a lot of problems raising money, so it was suggested, probably by Steve Rosen. (I was at the same meeting) that we split the AIPAC research department into two parts, a minor part to service the legislative lobbying, and the major part to become a 501(C)3 that could raise big bucks tax free unlike AIPAC itself which did not enjoy that tax status.
As you wrote, it was originally in AIPAC's building and on the same floor but we started getting a lot of pressure from some of the other Jewish organizations which were worried that AIPAC would cut into their (C)3 fundraising.
As for funding, the Weinbergs were key and even worked out a deal with some big money folks who didn't want to contribute to a political operation like AIPAC but would give to (C)3's. So one could give to the (C)3 and someone else would match it for AIPAC.
This became the ultimate in interlocking directorates.