Adding a link in addto-links
What is the standard procedure or the best solution to add a new link to the
Currently I have modified the following file
app/design/frontend/base/default/template/catalog/product/view/addto.phtml by adding an extra
<li> to the existing link.
What I am worried is whether this will affect future upgrades and if so, what could be the solution.
EDITED I need to add a link "Add to Favorites" near "Add to Wishlist" and "Add to Compare".
Never modify core code instead copy it to your active theme:
This will prevent any future upgrades from over writing your work and trying to hunt down changes you've made.
You can either implement the Add to Favorites by doing as you suggested with a copy of addto.phtml in your active theme.
Modify view.phtml and list.phtml and customize with CSS.