My site uses two menus (primary and secondary) when you scroll down the second one goes away. To remedy this I would like to pick a different menu for the sticky. Especially since the logo is an icon size I can fit more.
By default, the primary menu is the one that can be sticky.
Both the primary and secondary menus have identical options (colors, typography, layout etc..), so you could just switch the theme locations (Appearance > Menus) and change the settings for each so the secondary looks like the primary and the primary looks like the secondary?
Combining them isn’t really an option unless you get a little advanced and give specific menu items classes and show/hide them based on the sticky/non-sticky classes.
You might be able to make both menus sticky like this: