How to disable render for a particular form generated by other module

Hello everyone,

I want to use ajax with Invite module. So in block form and page form i have added one line $form['#ajax']['enabled'] = TRUE; because i need ajaxify both the forms but there are two problems i am facing which are listed below:

1.
Whenever there are some validation errors then it just show a red box and the box where we enter mail id red without listing error there.
2.

When there is valid id then it goes to the page associated with '#action' attribute. I don't want this functionality basically i want to disable render for this form but disable render only works for standard forms not the forms other modules can create.

Please help me out.