Replacing the cells in the Makita 24V screwdriver from NiCd to Li-Ion

Hello,
I have a screwdriver and a 24V NiCd drill and driver, very little used and in great condition, but the packages with cells were lost.
I can buy replacements and still have NiCd, but I happen to have 20 3.6V Li-Ion cells, unused. I decided to use them.

I will use 6 cells,

But I have a problem with charging. The original charging station is for NiCd, so it will not be useful, it will work, but if I forget to turn off, you know what will happen. So option number two is to mount the charger on the packet and simply charge it with a pulse charger. And here is the problem...

I have never met Li-Ion 6S charging control modules, i.e. for 6 cells.

They are on 1/2/3/4 and that's it.

Without etch design etc., wouldn't it be possible to use such a module:
https://abc-rc.pl/modul-ladowania-3s-12v

And connect one to 3 cells, and another three to another, connect the outputs in series to receive 24 V and connect it as a power supply?

I am a layman, I have no magical knowledge and I wonder if two packages connected in series can be safely used as one 24 V?

Will charging with a 24V impulse charger be ok? Is there more tension then and what?

The maximum safe charging voltage for 6S is 6 * 4.2V.

Hello - here are the security circuits for 6S
http://www.bto.pl/produkt/43164/pcml06s15723-dla-222v-5a
http://www.bto.pl/produkt/43434/pcml06s30d132-dla-222v30a

And in my power tools, I replaced the NI-CD batteries with LI-ION, because I use them quite rarely and whenever they were needed, the batteries were dead. As the batteries were different for individual devices, from 7.2 to 18 [V], I decided to buy a microprocessor charger to charge all cells. It also functions as a rectifier for charging Pb 5 [A] batteries - it recognizes the 6 or 12 [V] battery itself and an adjustable laboratory power supply. In the batteries, I connect the controller sockets to individual cells, which I lead outside the battery. Since I had the cells for free from disassembled laptop batteries, I calculated that when I buy such a charger, it would be as if I had to buy NI-CD cells for one equipment and I safely charge all the batteries with one charger. My charger can charge up to 6 Li-Ion cells. I think such options can be considered.