related column contents
First, yes it is possible to make sure changing a column in one table gets updated in all related tables. The concept is defined as a Foreign Key. In MySQL, the tables must be using the InnoDB storage engine. Here is the link to the 5.5 documentation on implementing foreign keys.

The basic gist is your child table (the table that relies on a foreign table's column value) needs to have this done to it:

ALTER TABLE bar ADD CONSTRAINT fk_foo FOREIGN KEY foo_id 
 REFERENCES foo (foo_id) ON DELETE CASCADE ON UPDATE CASCADE


Where foo_id exists in both the child table bar and the parent table foo. The foo_id column must be defined exactly the same in both tables (same size, type and unsigned/signed status).

Secondly, I would highly suggest not basing your order of visits on the auto-increment value.  Auto-increment columns should have no meaning to your data.

If you have a date column, you should be able to get the order based on that column + the visitor, even if you add it manually at a later date. This would remove the 'need' of updating the autoincrement value.