Possible Setup? stand alone server replicating bidirectional to each cluster node

[Zak]

Our requirements are as follows,

There is a db server at each site located in a different town  to service the clients. 

 VPN is stable however chances  of an ISP or  DSL infrastructure fail are medium to low, ( Africa )

If there is a outage, no network coms due to DSL or ISP, the server still functions as stand alone server which stores the write logs until it can resync.

We are running MySql circular replication with alot of stability problems, at times it fails to replicate without errors. 

Percona Cluster seems to be the solution with only limitation that I need to overcome. 

with the cluster setup, each node is deployed at branch level to serve its clients.  if a nodes goes down due to a loss in network comms ( VPN goes down, ISP, DSL  ) 

it becomes unavailable, non primary. If i force it to go online, it will become its own primary node and still have inconsistent data with the rest of the cluster

I read articles of   a stand alone server to the cluster replicating bidirectional ,but what about a stand alone server replicating to each cluster node which is located in its own segment.

If this is possible the cluster will keep data in sync and each node will async replicate to the the stand alone data. writes will then replicate back from the stand alone to the cluster.

Or is there any other solutions I am missing?  the server has to operate in öfflinë" mode until it can resync with the cluster if there is a loss in comms.

Zak