Sounds good SM,also maybe try swapping blankets/toys etc and like Chrissy says give them both lots of fun play together and make sure they have an "escape route" if things get too heated,also a bit of rescue/calm remedy may help ease the tensions,it'll just be slowly,slowly as they are both of an age where they are used to having everything on their own terms but if you distract them with other more fun pass times,they'll maybe realise that being around each other isn't so bad
Good luck and let us know how you and they get on,Elvis is gorgeous btw