Maybe.. can't really say unless I know the tables teh contnet then linksand what you want to get out of them. The theory is that using a command you can write a SQL statement that has a bit more control on the join and selections.
Which table has the "missing records" in it? If you can track where the exclusion is occuring you can focus altering your process to account for that.
To change these to outer joins you may need to remove all of the links
and start your join process from scratch. (at the vary least romve your join from z to X)
Please keep in mind that I am guessing at this. Without the tables and you desired data output that is the best I can do...Maybe this....?????
x outer left join to y
y outer right join to z
z inner join to x