By analysing the verbatim of the bare act it could be understood that the three of them are related in the context of deciding over the existence of a particular custom or a right. Section 13 talks about the things or the necessary conditions or the prerequisite facts to be considered while deciding on the existence of a particular right or custom. Since a custom is usually a defined as a traditional and widely accepted way of doing a specific thing in a particular society, place or time, which means for evaluating someone’s right or a custom to do a particular job is related to time per se, due to this same reason for courts to establish a particular custom they usually take in account whether there was any transaction which could help in establishing a right or custom which is mentioned in 13(a), for the same if any person who cannot be called as a witness according to the section 32 of the Indian evidence act, their statements can be accounted when it is in relation of determining the continuance of a custom or right according to section 32(7). However, the court when wants to form an opinion regarding the existence of a right or custom then the court has the power to take in consideration the opinions of the local people which can help in determining the same.
According to my understanding of the three sections Section 13 acts has a broader ambit where the prerequisites or necessary facts for deciding over existence of custom or right is mentioned about and one such condition can be satisfied by using the statement by a man who cannot testify due to him bring dead or other such conditions mentioned in the section 32(7),the section 48 acts as an additional evidence in the means of opinions of local people used by the court in order to form an outlook of the continuance of an right or custom along with the section 13.
section 13 = existence of custom
section 48 = continuance of a custom