(based on Shul Chatam Sofer, Choshen Mishpat 95)

Case: Reuven sold to Shimon, in order to help make a living, two seats in shul: one in the men’s section and one in the women’s section. Levi, who holds the neighboring seat in the men’s section, wants to employ the rules of bar metzra (the special rule by which the neighbor of property that is sold can pay its price and take the property from a non-neighbor buyer).

Ruling: The querying rabbi suggested that it is possible that bar metzra does not apply if Levi is the bar metzra only of half of the sale, and in the case of doubt, we should say that Shimon is muchzak (is in possession of the property until proven otherwise) and can claim kim li (i.e., "I want to follow the minority opinion"). However, it is incorrect to apply the rules of muchzak here because in cases where bar metzra applies, the buyer is considered as if he is acting on behalf of the neighbor. Thus, according to the opinions that bar metzra applies, Levi would actually be the muchzak.
He also raised the logic that bar metzra does not apply when the seller needs the money for food to eat because then we cannot expect him to consult first with favored buyers. However, in this case, Reuven did not have a short-term shortage of food, just that he wanted to use the proceeds of the sale for business needs. If we would say that such cases are also excluded from bar metzra, then we would all but erase the halachot of bar metzra, as almost all sellers are in similar circumstances to that of Reuven.
The Rivash says (see S’ma 175:99) that when there is a separation between the properties of more than a tefach, the laws of bar metzra do not apply. However, that is not an issue here, certainly if Levi wants to remove the separation and expand his seat. Even if he wants to keep the separation, he can still say that he wants places in shul that are near each other, which is a desirable situation for relatives (see Rama, Choshen Mishpat 175:13).
We should take a better look at the claim that one cannot claim bar metzra in a case like this where Levi is a neighbor only of the seat in the men’s section. If the minhag is that each seat in one section has a corresponding seat in the other section, then it should be considered like one big field, and Levi should be able to make a claim on the pair of seats. However, if they are generally unconnected to each other but were sold in this specific case as one unit, then we should say that Levi cannot claim bar metzra rights even on the seat in the men’s section (see S’ma 175:22).