formula for picking up data which is missing in the table

i Have been using "=A3" type of formula to pick up data from the unique function for
my Vlookup Table as there are to many entries to do in a day that maunally entering them will take ages...
and on the regular bases i have to edit or delete the data from the main table which leads to
readjustments in the answers of the UNIQUE Function... so i often copy and paste(value from '=A3' which was used to pick up the UNIQUE function)
which leaves many holes in the table if the party name is removed or edited
so if anyone can help me with a formula or function or any option to pick up data which dosen't change upon edit/delete of data from main table
or provide a formula so i can pick up data from the unique fuction except for the values already present in the coulmn

for refrence check the excel workbook i attached