bd50 to bd25 leave dubbed audio DTSMA & convert english DTSMA to ac3 bd-rebuilder

[agentsmith]

I'm trying to convert the DTS-MA of English into an AC3 (primary) and keep the dubbed language of a DTS-MA unchanged (secondary).

In bd rebuilder whenever I select Keep HD audio for BD25 /Alternate intact & selecting either french or English as default it keeps both as dtsma resulting in loss of video quality.

How would I convert the primary track to AC3 and keep the secondary track (DTS-MA) in it's original form?

[Music Fan]

If you don't need to keep menus, you can easily convert sound with eac3to and remux it with the video with TSMuxer.
You can also keep menus and re-incorporate the modified title but you will probably need BDedit which is not easy to use.