Plywood replacement can I mix with backer board?

[serval]

I've got a bathroom that was originally boarded out with ply and tiled over around the shower area.

Had to remove some tiles to replace a concealed shower valve and noticed the tiles in the wet area came off easily. Showing some badly water damaged ply.
I've cut these areas out and need to replace.

When it comes to replacing the bad sections would it be okay to use a backer board like jacko or similar butted up to the good sections of existing ply or should it be kept like for like to maintain consistency?

If I had time is likely remove the entire lot and reboard with a backer board but don't have time to re do the entire wall as there are tennants moving in an a few days so need to get something done fairly quick.
Thanks for any advice

 

[Kastar UK]

match the thickness(similar) with cement board and re-tile it , can use regular screws with cement board some backaboard need special fixings , tiled well with waterproof grout

 

[serval]

Thanks for confirming. Wasn't sure if I'd be inviting more problems due to the difference in flexibility between the existing ply and new cement board patches and how that might affect tile adhesion etc

 

[Kastar UK]

Thanks for confirming. Wasn't sure if I'd be inviting more problems due to the difference in flexibility between the existing ply and new cement board patches and how that might affect tile adhesion etc

welcome i would of said rip it all out and start over but for , you said ," If I had time is likely remove the entire lot and reboard with a backer board but don't have time to re do"