About join and relational data, you can take a look at R for DataScience chapter on it
Know that you have several verbs inner_join, full_join, right_join, left_join, semi_join, anti_join that depends how you want ot join your table. The book gives a nice introduction to those.
Also, if you us to help you with your example, you need to provide some data sample and code. A reproductible example would be perfect. (see reprex)