Would my maternal uncle's son be considered my maternal uncle (maternal aunt's husband/maternal uncle's wife) by virtue of my grandmother having breastfed him and my maternal aunt's daughter, given my grandmother's uncertainty?

If the maternal grandmother breastfeeds the son of her daughter's maternal uncle five full breastfeedings within two years, he becomes a brother to the mother through rada'a ( দুধভাই/fosterage) and a maternal uncle to the questioner through rada'a. Consequently, marriage between them is prohibited, while looking at each other and being in seclusion with each other become permissible, and the relationship of mahramiyya (being unmarriageable kin) is established. The grandmother's informing of the prohibitive suckling is sufficient to establish the prohibition. However, if there is doubt about the occurrence of the prohibitive suckling, the prohibition is not established, as the default is its absence.