When you merge duplicate contacts into a master record be careful when selecting the duplicate(s) to merge into the 'master' record.
Choose the record with the most up to date custom field information as the 'master' record. Then merge your duplicate record(s) into the 'master' so that you do not over-write any custom field information with that of the duplicates info.
This record will become the 'master' record and any duplicates will be merged into that 'master' record.
If merging a duplicate 'company' contact record into another 'company' contact then to be sure you do not accidentally lose any information make sure you have put the mode into 'individual person' mode if there are people contacts at that company.
To do this change the contacts view from 'Organisation' to 'Individual Person' mode using the button as shown below in red to toggle between the different views:
Find the individual people contacts at both companies you wish to combine together into just one company contact record.
You can then change the 'Organisation' name field for the contacts that should be part of the other duplicate company - so this would bring in those individual people into the one company contact record.
If you then search for the company name as shown below all individual contacts will be displayed:
This keeps all the individual people contacts together under one company. If you change to 'Organisation' view as shown below you will see the 'company' mode with the people at the organisation:
Just open up the 'company record' to view the individual people at the company:
If you have any questions or for help with merging please contact our support desk.