Not Making Relationship between Primary and Foreign key in S

Question

I have made a database and it is mature now , unfortunately I have mismatch column data types for my primary and foreign key relationship , Just like in my First table I have RecordsID as bigint and in my second table Where this REcordID is foreign key I have tinyint as datatype, my record is storing fine , Now i want to make a relationship but sql server 2012 does not allow me due to different data types of the columns , What would be the word around becasue if i want to change the data type to make both of them as same data type then i require  that change in many many stored procedure as well as in the code , tell me the word around , secondly as my data is storing correctly so if i do not make the relationship then what? because i am storing data using checkboxes so i am storing the correct values why to make the relationship if i do not make the relationship and what happens? as i have to create reports at the end so i need joins as well