Hi experts!
I really do need your help, since I don't know what else I could do
I'm building a custom form here.
Long story short:
There's 3 values assigned to the "Tipo Pagto" field:
Padrão, Cartão and Permuta.

If the current record of this field is set to Padrão o Permuta, the next 2 fields, "Dt Pagamento" and "Número Invoice" should be disabled, like the image bellow

But if Tipo Pagto is set to "Cartão", then, the 2 next fields, for the exactly same record should be available and updatable.
My current scenario is this:

When I set one to Cartão, it opens all rows and make it insertable aswell.
Also, when I fill the record where was Tipo Pagto as Cartão seted, and jump to the next record and change the value for Permuta or Padrão, the 1st record would now be disabled

Tried to use set_item_instance_property, but I'm on R12 and it doesn't work on it.
Tried SET_RECORD_PROPERTY, but then says that no field block exists.
Does someone has any tips?
Thanks in advance!