adding values to chosen cells from different sheets

Hello everyone I was wondering if you could help me with the following problem, I hope that I can explain it clearly.

Iīm doing a workbook for a local seafood company and Iīm having trouble with the unit transport part. In these workbook I have one sheet for every production facility ( I will call them A,B,C and D), each of these sheets contain the monthly production information for the different production groups (I will call them 1,2,3,etc), so for every group I must build one table that shows information like number of units, weight, growth, Transport, etc.
The main problem is the following, suppose I want to show the units (fishes) sent in january from facility A group 1 to facility B group 3 in February.
Something like this:

Sheet: A
Group: 1
Date: January February March April …
Units: 1000(-100) 10000 1000 2000
Transport: 100 50 60 20


Sheet: B
Group: 3
Date: January February March April …
Units: 1000 500(+100) 1000 2000
Transport: 100 50 60 20

So I must find a way to be able to choose where I want to send these units (facility B, Group 3) and automatically discount these units from the actual group and month, and then add them to the following month (February) for the selected destination.
I tried to make a drop down list with the possible destination but still couldnīt find a way.

I hope my explanation is not too confusing.
Please let me know if you have any ideas

Hi danielgp and welcome to the forum

Does "Transport Problem" mean you have a hard time getting to work? lol

we would love to help you, but 1st, according to forum rule 1, please rename your thread to something more meaningful, that actually describes your problem. lots of contributors will look at a thread title, and if it of interest to them, or falls within their area of expertise, and will only open those threads. also, searching for "help" will not turn up too many results that will benefit you, sorry

when you name a thread, think "google". what kind of returns would you expect if you typed that into google?

To change a Title on your post, click EDIT then Go Advanced and change your title, if 2 days have passed ask a moderator to do it for you."\