How to configure custom validations, enable a readonly filed while editing in Grid plus component?

I am building POC using a grid plus component, i need help solving below two issues

1. when i try to add custom validations like preparerDueDate<RevieweDueDate it does not validate properly. Even if one row has the validation to true, the message shows on all row for that field.

2. I have a column that cannot be edited when once added, when creating a new record i need the column to be editable. how can i achieve this functionality?

Thanks in Advance.