What is the ruling on a granddaughter sucking the breast of her sleeping grandmother, and does that make her a sister to her maternal uncles through fosterage, given that there was no intention or deliberate act of breastfeeding?

Intention is not a condition for fosterage (rada'ah). So, if a child is suckled five full feedings within the first two years of life, he becomes a son to the wet-nurse, and all those forbidden to her biological children by lineage become forbidden to him as well. If the act of suckling or the number of feedings (five feedings) is not established, then the prohibition is not affirmed, and any doubt about its occurrence is not taken into consideration. This is the preponderant view, held by Al-Shafi'i and Ahmad.