A little more information about what you are trying to do would be helpful.
If these are related records using matching key fields you could do the following:
1) Import the fields into the new main table. Keep the field names as is so you can import the data into the correct field by matching the name.
2) Import the records from the first table.
3) Import the records from the next table using the feature to update matching records and add additional records. Whenyou do this use the key field for the table as the match field and make sure that the field names match up so that the data goes into the correct field.. Repeat this for the rest of the tables.
Keep in mind that the resulting flattened or combined table will have a larger field count, so larger amounts of data must be cached each time a record from it is called across a network. Wider (more fields) tables can slow performance more than several narrower tables for the same data.