I have also done a SQL script for updating all active Group members and all Event Guests. You will need to change your moduleID's PortalIDs and insert the correct objQualifier. Ru nat own risk...
--update all active group members to be notified when there is a new post
insert into SmartThinker_WallSubscription (PortalID, ModuleID, RelatedID, UserID, Notify)
select 6, 1963, GroupID, GU.UserID, 1
from SmartThinker_GroupUser GU
--make sure this user exists
inner join users U on U.UserID = GU.UserID
inner join UserPortals UP on UP.UserID = GU.UserID
where not Exists(select SubscriptionID from SmartThinker_WallSubscription W where PortalID = 6 and moduleID = 1963 and RelatedID = GroupID and GU.UserID = W.UserID)
and Up.portalID = 6 and Up.Authorised = 1
and ApprovalStatusID = 1
--update all event guests to be notified when there is a new post
insert into SmartThinker_WallSubscription (PortalID, ModuleID, RelatedID, UserID, Notify)
select 6, 1971, eventID, EU.UserID, 1
from SmartThinker_EventUser EU
--make sure this user exists
inner join users U on U.UserID = EU.UserID
inner join UserPortals UP on UP.UserID = EU.UserID
where not Exists(select SubscriptionID from SmartThinker_WallSubscription W where PortalID = 6 and moduleID = 1971 and RelatedID = eventID and EU.UserID = W.UserID)
and Up.portalID = 6 and Up.Authorised = 1