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The people that seem to get "abused" are the ones that come asking questions but only want to hear ONE answer, and when they don't get that answer they begin a process of rephrasing the same question over and over trying to get that ONE answer that they want to hear, which will validate what it is they would like to do. Those types of people will have a problem and ask for advice, then argue with everyone who tries to help them. They have no idea what the problem is, but they are certain they know what it's NOT
You don't seem like one of those people at all, so I don't think you have to worry about being abused in any way. Do disagreements arise? Of course they do. I think some people can take things personally when someone disagrees with how they do things. I'm sure such people feel abused sometimes, but this is an online forum for the purpose of expressing ideas and sharing knowledge - SOMEONE is sure to disagree with SOMETHING along the way. It's no different than real life.
The last case of abuse that I can think of off the top of my head is the person that expresses an opinion but cannot defend their opinion when challenged. Opinions are challenged from time to time - that's all part of the information sharing that goes on. All we want to know is why someone thinks what they think or what led them to believe what they believe. I know for me, I'm hoping to learn something - we all have different experiences. it's not malicious
I think the 70L is already overstocked in that it's a small tank for mollies. It's not aweful, but they can get fairly large and in my experience a bit aggressive in a small tank when they grow up. They are group oriented fish, so it would be best to have more than 2. In my opinion, it would be better for you to return them and get platys or guppies instead. I think you can probably increase the tetras and the corys in the tank by a few each, assuming you don't have an odd shaped aquarium (as was already asked). That with a group of guppies would make a nice tank.
As for the 48L, I am assuming the corys are full size. I would switch them out for the pygmy corys and have the larger fish in the larger tank. Otherwise, I would just keep them at 3 because I don't think the tank is large enough to support any larger of a school. If you did switch them, I would only get 1, maybe 2 more of the larger corys, because the larger tank is still a bit small for them. I would do a similar swap with the penguin and glowlight tetras - put the larger fish in the larger tank. And as with the corys, if you swapped tetras I would get a few more penguins.