What is the ruling on abandonment in this case, and does the rejection of the wife's sister from his house continue as a fulfillment of his deceased father's wishes?

The reason behind the daughter's marriage without her father's consent should be considered. If it was due to her father's 'adhl (hindrance) and his prevention of her marriage to a suitable man she desired, then there is no sin upon her. The sin lies with her father who committed 'adhl, and it is not permissible to boycott her. However, if she married without her father's 'adhl, then she is sinful, having committed a major sin, and her marriage contract is invalid. In this case, it is permissible, rather, it is sunnah or even obligatory to boycott her. Her repentance will not be complete unless she rectifies this situation and renews her marriage contract with her first guardian after her father's death. If she repents and renews the contract, then it is not permissible to boycott her.