Loose the boots, and buy a new set of bigger straps for the cold season (boot season)
As very very few straps are good for handling both smaller feet natural, AND bigger feet with thick boots too.
Even if possible, they would be quite heavy and chunky often
Doing it that way, you can set both pairs up to fit you personally and perfect, so you dont have to waste a lot of time adjusting up and down and testing, when changing from summer to winther setup
Just an idea...
PS: I dont have the yellow one myself - is it an adjustable one, or fixed and adjustable only by moving screws ? North have both types.