Hallo,
Your subforms should be based on tables or queries which have a field (or several) in common with the table or query displayed in the main form.
If create the subforms first, then drag them into the main form, Access will set up the Child/Master link fields so that whenever the main form record changes, the subforms update to display the appropriate data.
ie. if you have a table of people with a PersonId (autonumber) and a table of pets indicating their OwnerId (the PersonId who owns them, base the pet subform on the pet table (no filtering), the main form on the person table, drag the pet subform onto the main form and the master link field will be set to PersonId and the child link field will be set to OwnerId and everything will be super,
- Frink