Is QGateNA a bound control because if it isn’t then you cannot do it,
as continuous forms are a devil of a thing to do anything with.

If it is a field then again you need to check it when you create the
record that is attached to KeyMilestonesSubID. Though if you cannot
do this you will need to loop through all records in your form looking
for KeyMilestonesSubID = 12 and then set the value of the field
QgateNA to true.

As for enabling and disabling again you cannot do it as if you enable
on button on a continuous form all are enabled and the same for
disabled

What I do when I want to do this is I add some code to the button or
field that if someone selects this field or clicks this button it
tells them it cannot do it

ie

private sub PassedQGDt_gotfocus()
if QgateNA.value = false then
msgbox “you cannot use this control”
end if
end sub

Hope this helps

Regards
Kelvan