Hi, first of all welcome to the server.
As far as I understand what you have posted above, that you are/maybe able to log two game windows to play together (Which means you either have a premium account for one of the two, or you have more than one PC). If this is the case, then congratulations, you can for sure making macros for your concern. However, the server doesn't have such function as you described " auto healing/buffing " , since the server has strict rules to punish bot, and any unauthorised third-party applications for cheating, and damaging the game justice. If this is not your intention, then you will have to make smart macros to help yourself to play. What you can do, is to create a macro that includes all the expected purpose and manually activate it to the char which you would like to receive the Healing/Buffs accordingly.
If you need a guide of macro commands, here is a website can help: Macro command list
Hope this helps. Enjoy your time here in l2classic.club