契

noun: contract; deed, adopted; sworn (kinship, e.g. foster parent/child)
契

2 candidate readings from Wiktionary — genuine Chaozhou colloquial form not yet confirmed by a speaker. Four additional candidates (siêg4, siag4, kiêg4, kiag4) were dropped because they are attested only for far rarer senses (an ancient personal name Xie; an alternative form of 挈), not the sense drafted here.