3 plus years? If I recall correctly your first snakes were royal pythons and you got them around January 2018. My apologies if I'm wrong on that but I think I remember your first post here, unless I have you mixed up with another.
I want to add a quick note on dropping a diamond (Morelia Spilota Spilota) into the mix whether it be soon or later.
You seem to like researching and learning about your reptiles which is good, we all should. The diamond pythons require some unique care and need some rather specific husbandry.
Years back some of us here on the board tried to help another member that unfortunately didn't want to listen to the care advice we were offering.
The snake was a rescue from another family member and sadly, it died.
IF you go the diamond route, you'll want a rather large enclosure eventually (adulthood) so you can have big gradients and various temperature zones. The care for diamond pythons differs greatly compared to the other carpets. They are beautiful snakes but you really need to be on point with their care. They are not widely kept because they are more involved than the other carpets.
19 animals seems like a lot to closely care for, but we all have our comfort zone when it comes to the hobby. I'm good with 4 and some people think that is a lot.
That aside, if you get into the morelia side of things please focus specifically on the care of the diamond pythons if that's your choice. It is not rocket science, however they require advanced care. My snake room won't allow me to care for a diamond properly IMO so I opted for a coastal instead. It's something to consider if you run your room at fairly constant temperatures.
Sorry to get off topic a bit. Whenever I hear about diamond pythons I'm reminded of the situation here years ago. Just make sure they are right for you and you for them.
Good luck with the collection!