>I have a form with 2 tables
>if I open a second form over it, when I get back
>to the first form, is not possible to find the tables.
>
>I think this is not the right way to do.
>
>What the right way to open a form over other form?
>
>I heard about child form. How that works?

You should either use private data session in both forms, or (if both forms modeless) open tables in some object (e.g. another form) with scope covered both forms, e.g. you may open tables in Top-Level form data environment.
If one of your form modal (called from another modeless form) then you may just use DE of the modeless form only.