Jenkins input pipeline step - Give submitter as a group
We have moved onto using Jenkins templates and I have a workaround to keep the individual approver names list in one place. Sharing the sample code for your reference.

#!/usr/bin/env groovy
import com.mm.Constants 
def call(String teamName = 'LOGIN') {
   // team name of null means UI
   teamName = teamName ?: 'UI'

   timeout(time:2, unit:'DAYS')
       {                                                              
           input message: 'Can you approve this ??', submitter: Constants."${teamName}_APPROVERS"
      }


}

#!/usr/bin/env groovy
class Constants {
   static final LOGIN_APPROVERS = 'approver1,approver2';
   static final UI_APPROVERS = 'approver2,approver3';
}


Below is how you call from the pipeline    

stage ('Ship to QA?'){
    echo "Waiting for QA approval"
    shipToQA('LOGIN')
}