There are three main issues:-
1) If the tables are matched against records in other tables then you need to preserve this relationship.
2) If you are going to append the tables into one new table then you may have a problem if a record from each table has the same record number. if you had a record number 1287 in each table, then after appending you would have two records with the same record number, which would not be good!
3) You will also require the new table to have a unique Auto number field. (A unique value for each of the records from the previously separate tables)
a) First thing to do is make a backup of your database and don't touch it!
b) Next you need to create a new field in each table to record the current Auto number identity field {for BOTH Tables}.
c) Now add another field, the purpose of this field is to record the identity of the two tables and preserve those identities in the new combined table. It could have a text value like "table 1" and "table 2" or you could have a numeric value like "1" & "2" (this would be the best option).
d) Create a new table, it must have an auto-number field with a unique ID.
e) Create all of the fields necessary to harbour all of the information from the previous two tables.
f) Append the information from the two separate tables into this new table.
g) Examine your other tables and identify the fields which contain the ID that matches the old unique ID from the two tables.
h) Create as many update queries as necessary to change the ID in each of your other tables to the new newly created unique record number field.