I've got Stempel Garamond, but every font belongs to a different family.

For it's more confortable ho have a unique family (I use it with LaTeX),

I tried to change the family name and the ttf name with FontForge

(not Stempel Garamond Roman and Stempel Garamond Italic as 2 different families,

but the same and only different subfamilies, Roman and Italic)

but, for instance, the italic is not recognized. Is there a simple procedure

to gain my goal? thanx

s

Where do the fonts come from? I would expect that the official Linotype release bought as complete family also has proper family style linking. And if not, I would contact Linotype about it. 

I always advise against changing font files directly. Fonts aren’t editable like RTF. You probably do more damage that “fixing” by opening and generating a new version. 

Yes, there are some fonts having a single family for every weight, not only this one. My fonts come from Adobe Font Folio 11. It would be maybe possible changing only PS and TTF name, it worked well in the past for other ones, but now not. Or the matter is different, or I'm doing something wrong