Pairing clowns - Smaller fish being more dominant?

[mjt82]

Hello all - I mysteriously lost my female Picasso percula clownfish of about 10 years a few months back, and have gotten the male Picasso a new mate (an onyx variant percula). The established fish (assumedly the male from the old pair) is being dominated by the new fish. There is a significant size difference in the two - the new fish is maybe 1.5”, the older fish more like 2.5-3”.
An “x-factor” I can think of is that the smaller fish moved straight into a BTA and established a “home” faster than the larger fish did. Back story, this is all taking place as I am restarted my tank after a leak. Confusing enough??
Options I am considering:
1). Putting both fish in an isolation box with an egg crate divider.
2). Remove the smaller fish and isolate it, allow the larger fish to establish itself in the anemone (it REALLY wants to get to the nem, but the little fish is harassing it when it tries) then reintroduce the smaller fish.
3). Put both fish AND an anemone in an isolation box and let them hash it out. The box is fairly small, so I’m thinking this option may result in disaster.
Any opinions? Thanks in advance!

 

[Bryn]

From reading about Clowns, as I have a Lightning Maroon that I'm thinking of pairing, I wonder if you also need to rearrange the tank first, let the older Clown become established in the BTA but in a different part f the tank, move aquascape around a little, and then introduce the younger Clown.