Questions on Holdco equity structures

I currently own and manage a B2B service company with a partner. We're rapidly growing and potentially taking on investment. We also have a small add-on acquisition we're looking at.

My thought is to create a holding company that my partner and I own 100%. I assume the Holdco would own minimum 51% of the original B2B service company and allow the remaining 49% for potential investment funding equity. And then do the same for the add-on acquisition.

Is my thinking correct on this? And how is this structure viewed by potential investors to the subsidiary companies?