I have come close to dropping Mya also at times, and actually one time my friend was holding her and she sprung out and thank god landed on grass and on her feet. I have made sure to tell people how to hold her.
I do the straddling my arm thing too, except I don't need to use the other arm as she isn't too big yet (3.5 months). But I definitely agree, by disabling her legs from springing I have saved her from being dropped a few times.
Plus her straddling my arm is actually really cute and people get a kick out of it

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