Forms :: Entering Multiple Data In A Form Containing 4 Blocks

I have 4 blocks in my form which is basically used for travel booking for the employees in a company within India

1) Header block :- contains info abt the person who is booking the tickets for number of employees. Here i have given booking no a primary key.

2) Employee Detail :- Here the basic info of an employee is entered. Here i have taken booking number as a foreign key and then given emp_cd & booking number as a composite primary key.

3) Travel Detail :- Here the travel detail of individual employee will be entered wherein a unique trv_no will b generated 4 every single travel. Again i have taken foreign key as bkng_no frm 1st blck and emp_cd frm 2nd blck and tkn a composite primary key which comprises of bk_no,emp_cd and trv_no. this is used to maintain the uniqueness for single travel.

4) Vehicle Hotel Details :- This block is placed on different canvas for same form.It is meant for Other details in which details regarding hotel,vehicle etc booking aftr reaching the destination is entered. In this block thrs no primary key, but i hv taken the composite primary key of 3rd block as a foreign key since thr will be multiple entries for this one entire travel.

At every level there will be multiple entries for each corresponding entered record. I am able to enter one single record properly i.e. for 1 emp i am able to enter multiple travel details and his other requirements but asi try to enter more then one employee info, his travel details, other requirements i face an error stating foreign key constraint violated.Parent key not found for 3 rd level block.

How can i get the desired o/p wherein all the multiple records for every single subsequent record are stored correctly taking all the constraints in to consideration.