implementing referntial integrity with php mysqli

i have three tabs in my Db:

1.pers_info(id(primary), name ,....) 2.contacts(c_id(primary), phone, email, ...) 

now 1 person can have multiple rows in contacts tab. thus to minimize redundancy i made another tab contact_relation(id (foregin key references pers_info(id), c_id (foregin key references contacts(c_id))

i successfully created the relation and also was able to insert apt entries(related id and c_id) to it "using last_insert_id();" to extract id and c_id required.

now the problem..

i dropped tab contacts_rel. and created it this way :

CREATE TABLE contacts_relation ( id INT NOT NULL, cid INT NOT NULL, FOREIGN KEY (id) REFERENCES pers_info(id) ON UPDATE CASCADE ON DELETE RESTRICT, FOREIGN KEY (c_id) REFERENCES contacts(c_id) ); 

if now i try to insert into tab cont_rel, it gives error : cannot add or update a child row foreign key constraint fails. which makes sense..

i was hoping that adding constraints in the defn of tab cont_rel would save the hassle of inserting entries in it manually using "last_insert_id();"

so is there a way, i could maintain ref integrity with new data coming.. thanks.