I see.
It should be easy to add a script feature, for example, grab one animation and assign it to another. Since it only modifies modeldata, it would be relatively safer than modifying model directly.
void a = getentityproperty(ent, "animhandle", openborconstant("ANI_WALK"));
changeentityproperty(ent, "animhandle", openborconstant("ANI_FOLLOW1"), a);
And for model txt solution, there is already a @include tag which you can import any text file.
For example
anim walk
### save below as data/chars/a/walk.txt ####
delay 5
bbox 0 0 20 60
frame data/chars/a/1
frame data/chars/a/2
frame data/chars/a/3
frame data/chars/a/4
frame data/chars/a/5
################################
anim walk
@include data/chars/a/walk.txt
anim idle
@include data/chars/a/walk.txt
anim follow1
@include data/chars/a/walk.txt