Change behavior of fields in another form based on id of another table

Hi Ktommy, Vladimir
I'm not quite sure I understood your attached example but it seems, at its core, that you want to hide / reveal various objects depending on a selected value in a combobox or tablegrid.
It doesn't matter whether the objects are on the same Form or on a different one - the syntax is the same.
Have a look at the attachment for some suggestions.
In Selection1, depending on the value selected in the combobox, diffferent tablegrids are hidden / revealed, a button is revealed and on a second Form, one of the fields is hidden.
In Selection2, depending on the value selected in the combobox, wholly different Forms are revealed so you don't have to worry about what objects are made visible or revealed;  obviously there is a bit more work to creating Forms specific to combobox selections (but you can copy / paste objects between forms so it's pretty quick) and it simplifies the script.
Like most things in MVD, there's usually a choice of how to achieve something.
One 'tip' - if you have a number of objects to be made visible / invisible, try placing panels on the Form and then adding objects to that panel.  Objects placed in panels are subordinate to the panel so you only need to make the panel visible / invisible rather than all the objects within that panel;  it can reduce the amount of code you need to write significantly.

Hope this helps,
Derek.

Hi,
Attached are a couple of examples of how you might do the sort of thing you're asking about (one uses panels, one uses tab sheets / page control). 
In both instances, selecting a record from the tablegrid displays different edit fields depending on 'machine type' or in the case of adding a new record, it is only after the machine type has been selected that a different selection of edit fields are presented.
The link through to the machine type can be derived either from Form1.tablegrid1 or from the machinetype that is displayed on Form2.  If your processing flow uses the same form that you use to add/edit records (ie Form2) then it is both easier and more efficient to pick the 'machinetype' value from there (it has to be there because that's how you would have selected the relevant 'machinetype' from a combobox in the first place when creating the 'model' record). 
If your processing flow doesn't use the form that you add/edit records on, then use Form1.tablegrid1 instead to derive the 'machinetype'.
Obviously the sample data I've used won't relate to your application but the principle is the same. 
Derek.

Hi,
If you could attach a sample project showing exactly what you're after, it would help to give you a more focused answer.
However, there are a couple of options that might be relevant (please see the attached).
Autofilla
1.  for a new record, either open the combobox  and select the customer or start typing the name of the customer.
2.  once your customer has been selected from the combobox, any other existing fields that you want to see from the selected customer record can be  retrieved using a script;  this is only relevant when adding a new invoice as it picks additional fields up automatically if you are in 'edit' mode.

Autofillb
1.  format the combobox so that not only the customer name but also the customer town and phone are available);  the added advantage of this is that you can start typing the name of the customer OR start typing the town  OR start typing the phone no'.  So if you want to see all your customers based in a certain town, for example, it is a very easy search.
2.  there is no script involved with this option.

But as I said at the start, depending on exactly what your scenario is, neither of these may be quite what you're after.
Derek.