Event about giving Ceci a gift in some area you've traveled to.
Then another event in any non-town area about clothes. (50 friendship.)
After Year 4, 6/1, gab to Mel for an event about adventuring with Ceci, then talk to Ceci. (60 friendship)
A few days later, invite Ceci (Mel must be in party).
30 days later, invite her again.
30 days later, invite her again for the ''Ambushed'' trophy. You'll fight a few Scarlets, which aren't too difficult at high levels.
If you don't want Mel's end to trigger, don't invite Ceci the third time. However, if you do, you can recruit Ceci (DLC/Plus/DX).
Defeat Evil Face by Frontier Village. Mel doesn't have to be in the party.