[mlangsdorf]

I would say if you're using your arms and your legs together, you halve both bonuses: +1 to hit and +1 to ST per extra leg.

Fliers characters shouldn't fall down when using their legs to grapple. That rule is inartfully written. It should probably say something close to "you can't use your legs for support" and elsewhere in the rules there would be a section about falling over if you're not supported. But I could see a normal person holding onto a dangling rope for support and grappling with their legs without falling over. Many fliers are in a similar situation and would be supported by their Flight.