Selected Answer
What makes Excel such a great tool is its capability to roll database, data entry, data evaluation and data presentation into one. Users don't have to learn the basics. However, just because Excel can do that doesn't mean that is the best way of doing it. The best way of doing a job isn't - and can't be - not to learn the basics.
With that said, my suggestion is not to filter. Your worksheet, obviously, is designed to present the data, either for the Electrical engineer or the Designer. So, where are the data? The data must be in a place where they are easily entered and modified. It is important that the database has no merged cells. However, once you design it as a database that bit usually comes by itself.
Then you create two worksheets, one for the engineer, the other for the designer. Both draw on the database, so that when a change occurs in the DB it is reflected in both sheets (or in the appropriate sheet).
Your problem therefore isn't one of filtering data (because you don't have a database) it is one of workbook design. You should separate data base from data presentation. Usually, in Excel, data entry (and data modification) goes with the database. I suspect that your work flow intends data to be modified in the filtered presentation sheets. That can be done too, but at significant additional effort. If your DB is so complicated that it needs a form for the user to enter data correctly, consider creating a form to enter and modify data correctly. Bear in mind that it is the multi-purposing - using the same form for entry, modification and presentation - which is creating problems.
The final point I want to make here is that work flow and workbook design are closely related. If you would post a copy of your workbook with your question I might be able to advise you on how to split data from presentation but not knowing your work flow my advice is likely to be less than perfect. Therefore I suggest that you design the database first, then data entry and data modification, and finally data presentation. Come here with questions how to get data into and out of your DB.
Sorry to give you this suggestion. You must feel that it isn't what you want. That feeling will disappear once you start enjoying the benefits of a better workbook design. Not only is everything easier to do but many things become possible which were quite unthinkable before. Moreover, it isn't very hard to do because most of the underlying analysis has already been done. It must only be put together differently.
