Is it permissible for a man to give his daughter in marriage to his father's maternal uncle?
Is it permissible for a man to marry (Part No. 18; Page No. 205) his cousin who suckled with him one day or part of a day?
As for the first question, it is not permissible for the questioner to give his daughter in marriage to his father's maternal uncle because his uncle is considered an uncle to him and to his offspring and their succession because of the general meaning of Allah's saying (Exalted be He):
...your sister’s daughters
The uncle is not allowed to marry his nieces and their descendants. As for the second question, if the number of suckling reaches five times or more during the first two years of life, the suckling will make him a Mahram (unmarriageable relative) to her. It is not permissible for the questioner to marry his cousin who suckled with him or with one of his brothers. If it is less than five times or after the first two years, it will be ineffective. The legally counted suckle is that a child suckles milk from a woman's breast and when he leaves the breast, it will be considered one suckle. If he holds it again, it will be a second time and so on until he completes five times. This is the shar`y counted suckle; not the one which you described in one day or part of the day because a baby may complete what is considered suckling in less than an hour or he may complete it in five days or more. (Part No. 18; Page No. 206) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.