Yes you can do that. In AEM 6.1 you can add multiple LDAP identity provider configurations in /system/console/configMgr. If your user/group mapping is common across all the AD instances then just define one single sync handler configuration for the user/group mapping and give it a name. Then create identity provider and login module configuration for all ADs. You need to map each login module with the common sync handler and identity provider names you have already created. You can do all of this in Felix console configuration manager.
The details of the configuration can be found here - https://docs.adobe.com/docs/en/aem/6-1/administer/security/ldap-config.html
Actually we have 4 to 5 AD currently as per each market and there are different users/group for each market but few users/group are commons as well.
Can we also configured multiple sync handler in case of different user/groups right?
Can we also integrate other AD server like SOX instead of LDAP?