Add custom property

$Group = Get-ADGroup <group-name> -Properties * -Server <domain>
$Group | Set-ADGroup -Add @{ gidNumber = '3000999999' }

Update existing entry

$Group = Get-ADGroup <group-name> -Properties * -Server <domain>
$Group | Set-ADGroup -Replace @{ gidNumber = '300099999' }

Find groups based on a property

Get-ADGroup -Filter "gidNumber -eq 300099999" -Server <domain> -Properties *

Add member to group

Add-ADGroupMember -Server <domain> -Identity <groupname> -Members <userid>

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