double first base questions

[nickdangerME]

Fed rules, B1 hits grounder to F6. Throw is well in time but a bit high, hitting top of F3's mitt and popping nearly straight up. F3 leaps up to catch ball and does so, but her foot comes down entirely on orange side of double first base, just before B1 hits bag on the seam between orange and white. What's the right call? Would it have made a difference if B1 had hit only the white of the bag?

It was not a game-turning call, but I called B1 safe. My thought was that the throw was not from foul territory, nor was it really the throw that drew F3 into foul territory. In my mind, she could have either made the original catch with a bit more care or caught the rebound without leaping onto the orange.

I didn't find much on the doublefirst base in the rules or casebook - maybe I missed it. I know the throw from foul territory lets F3 use the orange (and B1 use the white or orange), but what about a throw from fair territory drawing the fielder off the white?

Nick