Its good, so clearly I wasn't .... Ah well
It is working for me now.
I am not sure the add file is working properly but it may be the way I am using it.
If you create a folder, mine is HMI_Main with HMI_Main.ino in it and then add additional .ino files, blanc or otherwise, they open automatically with HMI_Main.
Saving is the same, a save command saves everything.
Exactly what I wanted.
Thanks both, I would have given up on that without the assurance that I wasn't trying to do stuff that didn't make sense, again!!