Mo,
>I tried to mix the mix the xxx.VCT with old version of xxx.VCX but that caused an error.
That won't work because the memo pointers will all be off.
>my question. is there a way to build xxx.VCX from the xxx.VCT???
Not really. If you happen to have built an APP or EXE you can go into either of those files and pull out the VCX and VCT. Refox can do this for you. Otherwise you can do it by hand with a little spelunking using hexedit.app