8.1.3 : Synchronising samaAccountName to Azure AD


We have version 8.1.3 and the AADUser schema does not support the field onPremisesSamAccountName . 

We want to send the samaAccountName from AD to Azure AD using OIM...we are planing to upgrade to 8.2 in next months but we need this field in Azure AD urgently..

Is there any other way we can push this attribute using OIM ?

I know there is Ad connect can help but we don t have much experience using it .. 

Using code, it seems to be impossible as the Azure AD  onPremisesSamAccountName is read only..

I'm definitely looking to a mean to do it using OIM (jobs, script, Graph API or any other way) ..if of course possible

Many thank by advance