There are two issues here.  The first one is identifying the correct group.  Your English description doesn't match the code.  Your English description says that the records should have the...

A foreign key references a unique key.  It doesn't necessarily have to be the primary key.

Drew

Assuming that the data is already summarized by month, you just need to COUNT(<some field> ) OVER(PARTITION BY <partition fields> ORDER BY <date field> ROWS BETWEEN 11 PRECEDING AND CURRENT...

First, this is not the best way to post sample data.  I've created a quick and dirty method of doing it, because I'm a bit short on time.

The closest thing is Merge Replication.  I've never used it, so I can't tell you much more.

Drew

You haven't gotten a response, because you haven't supplied readily consumable sample data and expected results.  (A picture is not consumable.)  If you follow the instructions in the first link...

I don't think that you want to be using a sub-query at all.  Try the following.

UPDATE L
SET LOTTABLE05 = I.LOTTABLE05
FROM WMWHSE1.ITRN I
JOIN...