How do you punctuate a sentence with two separate quotations separated by a conjunction?

An example would be the sentence:

They were saying, "He’s too young to be working so many hours," and, "He should be focusing on his schoolwork."

I would think that, because these are two separate quotes, potentially said by different people since they’re attributed to a generic "they" (ostensibly a group of people all saying similar things), there should be commas both before the conjunction as at the end of any quotation, as well as after the conjunction since it introduces a new quotation. I would also think both quotes should be introduced with uppercase letters since they are distinct. But I’m having a hard time finding this particular situation addressed in online grammar guides. What’s the proper placement for the commas in this sentence?