The jamb to jamb measurement is not what normally changes with a replacement window project. It is the jamb depth and there is no modification to the blind itself that makes that any different. Most times, even with the change in jamb depth, the blind can be re-mounted with offset brackets or just some movement of the blind bracket.

Good to know, thanks for the info. Every person that came out said specifically said that any inside mounted window coverings would not be guaranteed to fit. They're usually ok, but there's always a chance. For most, I don't actually care, but the one we have in the bedroom is one I want to keep so I think they're going to do what they can to accommodate that one unless of course it would cost me another $500 to make the opening larger.

They usually just need to be spaced out is all in this case. As window installers, we very ardently maintain that we are not responsible for guaranteeing the fit of the old blinds or even re-fitting them. That said, most can be re-fit with some tweaking. It is just something that we don't want to be held too because we cannot know how they were installed before.

As an fyi, i called the place I bought them, and they can be trimmed if need be. They dont do them in house house, but are able to send them out. Just posting the update in case others inquire as well.