Missing fonts replacement

Is it possible to replace missing fonts in Dorico formerly used by Sibelius ? I´m using MacOS

You can’t use Sibelius’s music fonts in Dorico, because Dorico uses a totally different font standard for music symbols, and so it looks for the symbols in different character positions. (They actually invented the standard, to incorporate 1000s of music symbols into one font. It’s called SMuFL, and a standard that other apps are starting to follow.)

Any text fonts that you own which are installed in your system should be available to Dorico (as with every other app).

Which fonts are you referring to particularly?

Hi cheekhome and welcome to the forum!
Are you talking about text fonts or music fonts? If the latter, Dorico uses the SMuFL font format, and you’ll find some other fonts available (apart from Bravura and Petaluma included in Dorico). Check Notation Central’s website if you want to buy those.
If the former, Dorico will make any font in your Library/Fonts folder available.
You can choose which font will be used for what in different places in Dorico : Engrave mode>Engrave menu>Font Styles and Engrave mode>Engrave menu>Paragraph Styles. Of course, this advice only works if you’re working with Dorico Pro…
Not sure it helps. Can you be more specific about your needs (what version do you use, Pro, SE, LE?) and what kind of fonts are concerned?

PS : Ninja’d by Benwiggy