If the reviewers and editors setup is default then the changes by different
contributors should be displayed differently, i.e. different colours and also
a user name (taken from the Word User Information), so they should see the
difference between yours and others changes.
As to explicit formatting, AFAIK the Changed Lines cannot be assigned to a
style/format. You could create a Character style with say highlight/font
colour/etc. assigned for contrast, but this could confuse the reviewers.
As you say the reviewers are planning to use Track Changes, therefore it
implies that they are used to its foibles.
If you do find out if Changed lines can be assigned to a style/format,
please repost here for future reference.
All the best
DeanH