Q. Re- Above question on a kinyan (acquisitive act) for the matzos eaten at the seder by family and guests. Should that kinyan be done for them in mind, at the time the host buys his matzos?
Does that apply also to the maror?
A. Mishna Berura (454: 4), advises that when buying matzos, the buyer should be careful to pay for the matzos and not buy on credit, if the seller mentions that he needs the money, as he may not be acquiring those matzos until fully paid. However as mentioned in the above questions, there is no need to buy for the guests or the family.
Horav Shlomo Miller’s Shlit’a opinion is that it could be paid by cheque or by an accepted credit card.
As far as maror is concerned, although Poskim disagree, it is better if it is one’s property, since there is a hekesh or link between matza and maror. (Biur Halacha 454: 4 quoting Pri Chadash).
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a