Can you help me to knw how to give access for selected user via custom field in particular project ?

[Abdul Rehman Shaikh]

Can you help me to know how to give access for selected user via custom field in particular project ?

For Example : i have create change request selection field in which i required Manager X and Manager Y to approved it, and this only two should be visible in that field.

[Joe Pitt]

This is how I handled a similar problem

Approvals

You want several groups to approve an issue before proceeding. It requires a bit of work on the workflow, but simple stuff.  I use project roles for user permissions.

 Create a select list for each area with N/A, Yes, No options

Create a transition from the status where you want them to approve for each group with the condition of only users in 'that' project role can execute it and the related select list must be empty. Each group will only see their transition and it isn't set. Have the transition go back to the initial status.

 As each group completes the goes through their transition to approve or deny the transitions will disappear.