1. change all able sister designs for umbrellas, dresses or hats
2.
a) choose a shirt to send, go buy it
b) write a letter, attach the shirt and save
c) TT forward to 4:58pm, and send the letter
d) wait till 5pm and go back to your town
e) find the villager that you sent the letter to
f) if he has the shirt, you are done, save and carry on
g) if he still has the old shirt, quit w/o saving and repeat the process from c
works like a charm, but they still can exchange shirts in conversations. it helps to not be idle outside constantly, that triggers villagers conversations. always go check their chit-chats, so they won't change catchphrases/shirts