Richard and Frances Klockner were the stepson and step-grandaughter of Edyth Klockner, to whom they were both very close. Both took care of her in the final years of her life, and, to reward them, she offered to change her will so that they would inherit her property provided that they continued to care for her.
Edyth knew that Richard and Frances took care of her out of love and affection, but she also wanted to give them the additional motive of the inheritance to take care of her. Edyth had the new will drawn up, but did not sign it before she died (she thought signing a will was a premonition of death). Both Richard and Frances continued to take care of Edyth up to the time of her death.
Assume that neither language of Edyth's offer to change her will nor the surrounding circumstances indicated whether the offer invited an acceptance by making a promise to continue to take care of Edyth, or by performance "by continuing to take care of her."
Then, Richard and Frances...
could accept the offer in any way and by any medium that is reasonable in the circumstances.
could accept the offer either by promising or by performing as they wished.