Good Morning,
I like the PS idea of a property form opening when activating an assembly. This allows the one assembly to be used with multiple take-offs (in this case footing size) creating really good data integrity.
Does ZZ Do this?

Watch my custom child assemblies, I think that is what your after. Its only 8 min. LINK
Yes we can do this feature, you can drag your assembly from the Templates onto as many Takeoffs on your pages as you need. Then double click the Assembly if the Takeoff sidebar to open the properties.