I’ve been meaning to connect both for a while, but I just couldn’t find a way to do so. If anyone could help me out, that would be fantastic, and many cookies will be given to you. Virtual cookies. Yum.
I’d personally say do away with the lower leg design entirely and build it out of Technic, but you may not have those. If you have four of the three long, half width technic liftarms with a peg hole in the middle and axle holes on the outside, you could use those and a balljoint from the Inika’s necks or most later BIONICLE titan’s feet.