Related for Moed Katan 45:5

How is it with marriage? It is forbidden to hold a marriage feast within the thirty days [of mourning], but if his meat is prepared⁴⁶Cf. Keth. 4a (Sonc. ed., p. 11). and his father or mother-in-law⁴⁷So GRA instead of V ‘father-in-law’, and again later in this paragraph. died, he brings the bride into the bridal chamber, performs the act of consummation and then separates himself from her [until] after the seven days.⁴⁸Only in an extreme contingency like this is a mourner permitted to hold the marriage-feast. When does this apply? Only if his father or mother-in-law died; but if his wife died, he is forbidden to remarry until three Festivals have gone by. R. Judah said: Until two Festivals have gone by, and he brings [her into the marital chamber] on the third. When does this apply? Only if he has children, but if he has no children or his children are young, it is permitted for him to remarry within thirty days.⁴⁹Cf. M.Ḳ. loc. cit. It happened that R. Ṭarfon’s wife died, and he said to her sister within the days of mourning, ‘Be my wife and bring up your sister’s children’. Nevertheless he did not cohabit with her until after the thirty days.