Multiple product sites visual appearance

So i am designing a website(lets call it mother site) which has multiple products(mobile apps), and each product(app) has a separate website for it. As a UX/UI designer, the entire responsibility is mine.
So the mothersite has one theme and colour scheme, and will display all the products, and the user can select any product and it will take them to the site for that product.

So the question is, should all the product sites have a common visual/user apperance? Or each product site can have a separate visual appearance?
And when i say visual appearance, i mean same type of header, same footer same overall experience, with just colour changes, and few necessary changes.

I am facing this problem beccause there are many factors which affect the credibility and market value of the entire product chain and the company itself.

PS: There are different colours associated with each product. so colour scheme isnt my concern. If there is any confusion please let me know.