Hi,

You actually don't need to access the table to write to many2many fields. 
There are actually 0-6 numbers for representing each job for a many2many/ one2many field

(0, 0, { values }) -- link to a new record that needs to be created with the given values dictionary
(1, ID, { values }) -- update the linked record with id = ID (write values on it)
(2, ID) -- remove and delete the linked record with id = ID (calls unlink on ID, that will delete the object completely, and the link to it as well)
(3, ID) -- cut the link to the linked record with id = ID (delete the relationship between the two objects but does not delete the target object itself)
(4, ID) -- link to existing record with id = ID (adds a relationship)
(5) -- unlink all (like using (3,ID) for all linked records)
(6, 0, [IDs]) -- replace the list of linked IDs (like using (5) then (4,ID) for each ID in the list of IDs)

Or you can use commands.
(0, 0, { values }) -- Command.create({...})
(1, ID, { values }) -- Command.update({...})
(2, ID) -- Command.delete(...)
(3, ID) -- Command.unlink(...)
(4, ID) -- Command.link(...)
(5) -- Command.clear()
(6, 0, [IDs]) -- Command.set([...])

You can give the code like:your_record.write({    'many2many_field': [(0, 0, { values })]}) or any one of the above.

Hope it helps