Manage customers with multi sale channels

I fixed the module base_partner_merge in OpenERP V6, it works fine now.
The module base_partner_merge_external_referentials extend it to works with base_external_referentials.
It blocks the merge of 2 external partners / addresses and update the refs in ir_model_data.
Both are available in extra-addons v6.

So this a good way to manage afterwards customer created from Magento and from within the ERP.

A more proactive way could be the following one, but I think the merge is sufficient and this one is maybe not really realistic because we can't ask for the email of each new created partner in the ERP and the user won't necessarily use the same in the eshop:
"Of course, we assume that the the email is known when we create the partner on OpenERP.
The emailid has to be editable.

When importing orders from Magento, if the partner doesn't exist yet in OpenERP, but a partner with the same emailid already exists (without external referential in the same shop), it must use it.

Be able to create / update a partner on Magento once it has been created in OpenERP.

A wizard asks for the store(s) where you want export the partner (as like as the product export wizard) and create or update the customer and his address on Magento."

The modules to merge the partners / address is good to correct dubbed partners.

I add a proactive measure (applicable for some business) :
The Magento email field on the partners is not anymore displayed read only.
When you create a partner, you have the possibility to fill this field with the customer's mail.
When magentoerpconnect will import the customer from magento for the first time, he will be bound with the latter partner which has the same email.

In a future, this field manually filled on partners could be used as Magento's mail ID for partners exports.