I can totally understand the reasons why they initially felt it might be best to send each child to her father's people - sometimes practically has to win out. It's the casual way in which it is discussed that really struck me, though, not the slightest consideration given to the fact that the girls are sisters and each of them is all the other has, now they are orphans, so that separating them is going to be an additional trauma for them. It is no doubt a very accurate reading on how such a situation would have been handled at the time, it just reads as quite cold.
But then Jean is later so concerned for Kirsty, and takes her on so willingly after all, that it makes up for the initial coldness.
I think the perception was that orphans were lucky to have somewhere to go at all and that having food and clothes were the priority. I don't think Jean's attitude to Kirsty is kind or understanding but it is realistic. Jean is flawed and I think views Kirsty as a bumptious brat who needs taking down a peg or two. Plus there is the whole clannishness attitude. I think one of the book's strengths is that Jean makes mistakes and grows as a person so by the end she can care for Kirsty without a blood-tie.
I love this and wish it had been allowed a proper ending.