Modify membership on dynamic distribution group

Hi all,

First of all, apologies if my question is really noobish but I am a total beginner in PS.
A third party to our company once created some dynamic distribution lists and now we need to modify the membership of some of them. We are on Office365 and cannot have access to ECP, so I would need to do this via PS.

The string in the “Asia” dynamic distribution list is the following:

((((((((RecipientType -eq ‘UserMailbox’) -and (((((((((City -eq ‘Singapore’) -or (City -eq ‘Shanghai’))) -or (City -eq ‘Taiwan’))) -or (City -eq ‘Hong Kong’))) -or (City -eq ‘Seoul’))))) -and (-not(RecipientTypeDetailsValue -eq ‘SharedMailbox’)))) -and (-not(RecipientTypeDetailsValue -eq ‘RoomMailbox’)))) -and (-not(Name -like ‘SystemMailbox{')) -and (-not(Name -like 'CAS_{’)) -and (-not(RecipientTypeDetailsValue -eq ‘MailboxPlan’)) -and (-not(RecipientTypeDetailsValue -eq ‘DiscoveryMailbox’)) -and (-not(RecipientTypeDetailsValue -eq ‘PublicFolderMailbox’)) -and (-not(RecipientTypeDetailsValue -eq ‘ArbitrationMailbox’)) -and (-not(RecipientTypeDetailsValue -eq ‘AuditLogMailbox’)))

I want to add another city, “Tokyo”, so all users’ mailboxes where its office appears as Tokyo will be included. I know I should use set-dynamicdistributiongroup but how should be the syntax to add this?