What you’re better off doing is using one larger charger in conjunction, like a 3A 12S charger, and connect that to the main leads.
Then use your tiny chargers once the pack overall reaches ~90% capacity. That’ll just be a small current balance.
You could have some sort of zener diode hooked up to the main battery positive and use that to switch a relay or something to switch between the large and the small chargers once the pack reaches a certain point.
But honestly at this point I’m describing a dumbed down balance charger with way less safety features.
Just get a 12S charger and use an external BMS and plug the balance leads into it.
Better yet, just stick a balance board up to the balance leads and keep it inside your board. They’re super tiny and thin, very cheap, and has zero of the failiure risks of using a BMS for discharge. Using this method you could just have one DC jack to charge with, IMO a much more aesthetically pleasing and useful method.