Trophy Question(Multi and Manaka)

Trophy Question(Multi and Manaka)

I'm trying to unlock trophies for Multi and Manaka.
The one for Multi is called: "I Won!",
And the one for Manaka is called: "I'm So Busy".
In order to earn these trophies, I need to, for Multi, Defeat your opponent with Serio's attack in Sisters' Housecleaning.(aka: defeat the enemy with her Splash Attack, BUT, Serio(the maid at the end of the line) needs to deliver the killing blow) and for Manaka, I need to Perform 5 moves from the front step/back step follow-ups after certain moves. Now, I read the descriptions on how to earn these trophies, but it's easier said than done!

I've tried using Multi's Splash attack to finish the enemy, but I can never get the Maid at the end of the line to deliver a successful killing blow. On account of the other Maids finishing him off before Serio can land the final hit.

Where as with Manaka, The description says I need to go from attacking to Front/Back Step 5 times During a single round. But, I don't know if I'm doing that Move correctly. I've tried it a few times, but I either keep getting interrupted, or I use the Move and it doesn't hit the enemy.

Can anyone explain this to me, as in what am I doing wrong?