Am I entitled to claim my share of the profits from the products that were the focus of the original partnership, and which my partner continued to sell with her sister and her sister's husband after our separation, and how can she clear her conscience if she does not remember the amount owed to me?

If the partnership was terminated in 2014, the sister must review the accounts to determine the amount of money and goods she had at that time, as she was the one collecting the money. In that case, you would be entitled to half of the cash and half of the goods. If it is difficult to ascertain this precisely, then reconciliation should be pursued.

If the sister traded with your money after that date, she has committed a wrong. In this situation, some jurists hold that the profit belongs to the owner of the capital, while others believe it belongs to the investor. The more authoritative opinion (al-rajih) is that the profit should be divided between you as in a Mudarabah (profit-sharing partnership), with 60% for the owner of the capital and 40% for the worker. This is the choice of Shaykh al-Islam Ibn Taymiyyah.

This applies if there is evidence that the sister invested your money or if she admits to it. However, if she denies it and you have no evidence, then you are only entitled to her oath, and you would receive only the original capital on which the company was liquidated in 2014.