Fixing/Removing all or many warnings is a more or less a one off job.

Most likely you will use other libraries, you own subclass layer and possible some special created of time.Maybe a your own framerwork.

When you have that all in MY_Dffallent, you first fix all/most of the warning in that one.
Yes that will included the old grids and maybe some other old, now flagged as history stuff.

It most likely have a variate of warnings.

Then that part is done. And will work, if you have multiple projects, for all.

Next is to concentrate on your application source code.
Yes that will give you many warning about grids. But you that is for you not a warning.
So you fix the ones you want to fix.

Long time ago I did fix up my code. I did warning by warning type. Was in the alpha stages of 19.1
But now you can use refactor and safe time.
Then just do the same warning by warning use the hot keys Ctrl+Alt+B and Ctrl+Alt+M
It is easier start at the bottom and use the back if case you have to add lines in the sources.

When all is done what you want to do. Set the project not to generate warnings. Is a quicker compile too

Peter