I think it suits the sentence, although I wouldn't say it myself, probably... that kinda sounds a bit military to me, like he received this message by some encrypted channels :D
Not sure what 'collecting' a message would mean exactly...
That would be a very specific reason not to accept "dziewczynki"... While it's true that "dziewczynka" is younger, we still accept "dziewczynki" here, it should have worked. But if you made a typo somewhere, then you probably got corrected to the main answer, which uses "dziewczyny".