Need to move values from Sheet 2 to to Sheet 1 based on matching adjacent column

I have attached what I am working on. It is to manually manage an inventory. Sheet one has a prodcut name in A, unique product identifier in B, A package size in C and a usage column in D. Sheet two will nave the name and ID in A and B, and a usage column in C. Sheet 2 will be populated daily via import from a report from another application.

Sheet 1 is the entire product list that is utilized. Sheet 2 from the report will be a subset of these based on daily usage. I need to update sheet 1 daily with a running usage

What I need to do is one of two things:

1. Move the usage values from sheet 2 to sheet 1 on a daily basis and put them in a new column. This needs to be done based on column B from sheet 2 matching column B from sheet one to get the correct usage on the correct row. In this case I would also add a column with a formula to add the two usage umbers together for a running total. This would take more work becuase those updated usage numbers would then need to be used the next day.

2. Move the usage values from sheet 2 to sheet 1 on a daily basis but have the usage added to the existing uage value in sheet one for a running total. Again, this needs to be done based on column B from sheet 2 matching column B from sheet one to get the correct usage on the correct row.

Can anyone help me with this? I don't know how to set up the matching criteria to populate the correct rows / cells.