Binding Multiple IDs Into Form With Two Parent / One Child Tables

I am very new to vb. I have to create a registration form based on the a complainant form and offender form. Complainant form fills out, take the complainant_ID and parse it to registration form to load. Now when the registration form loads, it has registration_Id and complainant_ID, fills out necessary info and add an offender from the offender form and pass back the offender_ID to the registration form..now on this registration form, we have registration_ID, complainant_ID, and offender_ID..complainant and offender can have more than one registration..

Table structures:
Complainant table(complaint_ID, last, first)
Offender table(offender_ID, last, first)
Registration table(registration_ID, complainant_ID, offender_ID, type, desc)

What I have done so far:
Using separate dataset for each form. Complainant/Offender/Registration form load and save fine. But I do not know how to bind these Ids together so they stay in sync.. What I mean, when I add new complainant, take the complainant_Id, parse it to registration to create a new registration for that particular complainant, and also add an offender to that newly created registration, and pass offender_ID back to registration form. I am using visual studio 5 and sql express..