Is it forbidden to use utensils bought with money jointly owned by relatives in the house, knowing that their value is equal to or greater than the value of the money paid by the user?

As for utensils shared by several individuals, it is permissible to use them if custom dictates leniency in that regard. Customary permission takes the place of actual permission, just as verse 61 of Surah An-Nur indicates the permissibility for a man to take from the wealth of his relative, agent, or friend what he knows they would be pleased with. However, the mother's justification for using the utensils is not a valid reason, for a partner may not use jointly owned property except with the explicit or customary permission of their co-owner.