A proprietor would not, for instance, allow the daughter of one of his serfs to marry a serf belonging to another proprietor--because he would thereby lose a female labourer--unless some compensation were offered.

The compensation might be a sum of money, or the affair might be arranged on the principle of reciprocity by the master of the bridegroom allowing one of his female serfs to marry a serf belonging to the master of the bride.
However advantageous the custom of living in large families may appear when regarded from the economic point of view, it has very serious defects, both theoretical and practical.
That families connected by the ties of blood-relationship and marriage can easily live together in harmony is one of those social axioms which are accepted universally and believed by nobody.

We all know by our own experience, or by that of others, that the friendly relations of two such families are greatly endangered by proximity of habitation.

To live in the same street is not advisable; to occupy adjoining houses is positively dangerous; and to live under the same roof is certainly fatal to prolonged amity.

There may be the very best intentions on both sides, and the arrangement may be inaugurated by the most gushing expressions of undying affection and by the discovery of innumerable secret affinities, but neither affinities, affection, nor good intentions can withstand the constant friction and occasional jerks which inevitably ensue.
Now the reader must endeavour to realise that Russian peasants, even when clad in sheep-skins, are human beings like ourselves.