What I suggest for doing Apotheosis with your marriage options:
Libra/Henry x Lissa(NosTank Owain)
Henry/Libra x Maribelle(NosTank Brady)
TBH these first two are interchangeable, so you can pick who you want to be stronger
Donnel x Sully(Offensive Galeforce or PavGis. Your choice.)
Vaike x Nowi(Sol, Luna, Armsthrift, Pavise, Assassin, and Dual Guard+.)
These two are also interchangeable, but Donnel x Nah is pretty bleh.
Chrom x Sumia(Cynthia gets everything she needs from Sumia anyways(Galeforce, Luna, Pavise), but Chrom gives her Aegis and Lucina gets the same thing.)
Frederick x Cherche(PavGis Gerome with Dual Guard+, and he already gets Sol)
Gaius x Tharja(Galeforce, Vantage, and Astra if you really want it. Noire gets Sorcerer + Luna/Pavise/Dual Guard+ from Tharja anyways, so...)
Virion x Olivia(Again, Inigo doesn't really need anything anyways but he gets Lifetaker and the option to go for a flying class.)
Ricken x Miriel(Luna and Dual Guard+, Aegis if you really want it)
Stahl x Cordelia(Severa gets even better with Stahl, as he gives her Luna, Vantage, and Assassin.)
Gregor x Panne(Yarne gets a big boost, with Sol, Armsthrift, Vantage and maybe Astra)
Again, all my opinion, but hopefully this helps.