Hello,
It's possible to do this using the Adaxes PowerShell module:
Export group members to a CSV file:
Get-AdmGroupMember "CN=Group,DC=domain,DC=com" -Recursive | Export-Csv "C:\members.csv" -NoTypeInformation
Add members to a group from a CSV file:
Import-Csv "C:\members.csv" | ForEach-Object {Add-AdmPrincipalGroupMembership $_.ObjectGuid -MemberOf "CN=Group2,DC=domain,DC=com"}