If Statement In Stored Procedures Help

Hi all. This has kept me up all night! I'm trying to populate a datgrid with multiple tables with relating keys in each table.

For ease, I've made the databases hopefully understandable.

DoctorsDB - (ID, Name, Phone)
FriendsDB - (ID, Name, Phone)
PetsDB - (ID, Name)
PeopleISawTodayDB - (MyID, MyName, DocID, FriendID, PetsID)

Now I need to generate a datagrid with the following details:
MyID, MyName, Doc's Name, Friend's Name, Pet's Name.

I have some success with the following code:

PROCEDURE dbo.PeopleISawTodayDB
@ID as Int
AS
BEGIN
SELECT
PeopleISawTodayDB.MyID, PeopleISawTodayDB.MyName, PeopleISawTodayDB.DocID, PeopleISawTodayDB.FriendID, PeopleISawTodayDB.PetID, DoctorsDB.ID, DoctorsDB.Name, FriendDB.ID, FriendDB.Name, PetDB.ID, PetDB.Name
FROM
PeopleISawTodayDB INNER JOIN
DoctorDB ON PeopleISawTodayDB.DocID = DoctorDB.ID INNER JOIN
FriendDB ON PeopleISawTodayDB.FriendID = FriendDB.ID INNER JOIN
PetDB ON PeopleISawTodayDB.PetID = Pet.ID
WHERE PeopleISawTodayDB.JobID=@ID
END



BUT it will only make a row appear if there are ID's in each of the PeopleISawTodayDB respective ID fields.

If I want to leave one blank (as in I didn't see that person that day), I would like it to still find the other details and populate the datagrid.

Can anyone lend a coding hand???? Cheers