Hi, first time poster hopefully someone can help and advise on this

I have a mailmerge to do for a client which is the equivalent to rent statements

the data has been supplied over 3 excel files and one word file with the placeholders there, it is the first time i have done this job and seems very complex but must be possible as someone (another company) has done previously

files - word template a 2pp document

excel file 1 - customer information data i.e. name, address, contact details, account number
excel file 2 - there rent type and basic cost information, data is sorted by keyfield however there are more records than file 1 but key field still exsists
excel file 3 - rent cost for the year, key field again supplied but rent information for one person goes over multiple lines and needs to display in table

help would be massively appreciated on this