i think u will need to go to the monitoring, find a pending activity, then click on "Re-evaluate Assignment(s) For User" to reevaluate all the assignments of an existing staff of the same department.

but it is very difficult to reevaluate the more than 100 pending dept request... is there any other way around that when ever we create new user and for same dept pending request should assign automatically

There could be a database based solution if you updated the assignment database table with the additional users but that goes beyond my sql skills - but it should be possible to build an app that does either that or executes the re-evaluation task for all activities via API: https://dev.joget.org/community/display/KBv5/JSON+API#JSONAPI-web/json/monitoring/activity/reevaluate

I think panda's answer is correct, you just need to do it once and not for every request.

OK - I thought Azhar tried it without success

I found this app in marketplace can help too.

Dears, there are more than 100 pending request with dept to complete, so reevaluate the 100 request is difficult job... is there any other way around. another problem is if your reevaluate the pending activity then it will be assigned to new user but other users may not be able to view the request

In https://dev.joget.org/community/display/KBv5/Running+Activity+Instance, there are 2 options. If you use the "Reassign User" option then you need to do it for each request. But for the "Re-evaluate Assignment(s) For User" option suggested by panda, you just need to do it one time for one existing user in the same department. It should re-evaluate all related tasks and assign the new user accordingly.