Mashup+world & world+world

Sooo first up, can I add a mashup like Realism Craft to Better on Bedrock before I make the same mistake like 10 minutes ago? I bought Aether Dimension 2 and thought I could add it to Better on Bedrock, but it doesn’t work. Then I searched on the internet and came to the conclusion that it’s because both addons are worlds. Is there still a way I can put them together so I can play Aether Dimension 2 and Better on Bedrock in one world?