It’s currently not supported.

a solution for this problem is :

a) create a view in database. the contens of this is a select idvalue, count(idvalue) as cuenta, from table1 group by idvalue,

b) call the grid by using a custom select sql with left join that include the table and the view including the field cuenta.

c) use custom css where the value is 1 or more (to highlight field ).

d) use custom add or edit to update the table1 correctly.

sorry for my bad english.

c) use custom css where the value is 2 or more (to highlight field ).