I investigated this concept for you a little bit. I believe macros could be linked, but it involves the use of two functions per link, depends on a few things being coincidentally true, and probably takes up about 100 characters, which is half of your macro gone right there.
Several AddOns make macro replacement a subgoal of theirs;
FlexBar is one example of a mod that has its own macro section, permitting macros of "unlimited length".
Flexbar is not particularly user-friendly, but I figure if you're courageous enough to play with macros in the first place, you can handle whatever the FlexTeam throws at you.