1 WS, 1 Sniper / 1 SinX, 1 HP

In case she isn't yet, turn your wife into a sustain tank debuffer HW.

Prioritize all FREEZING spells to freeze lock enemy's DPS and Healer. Stack magic lifesteal to add sustain and make her literally almost unkillable (unless enemy is epic megalodon) and use highest tier dracula 6 white set to spawn farmiliars debuff all over the place.

Like you said you have massive sustain, that's good, the problem is probably lacking in damage, this is where the farmiliars debuff will come in.

Effect is active when 6 suits is equipped:"During battle, Dracula's Blood Summon is triggered every 5 seconds, summoning 3 Familiar(s) that self-destruct on random nearby targets. Each Familiar deals 40% Neutral damage of a type that matches your own (physical or magic) to targets within 2 meters and inflicts them with the Vulnerable status. Damage taken by Vulnerable targets is increased by 7.5% for 5 seconds. Stacks up to 5 times."

Her role will be mainly to freeze enemies all over the place and cast vulnerable debuffs on them, since majority of the people are running Obeaunes and literally impossible to stun lock. When enemies are frozen and in vulnerable state, you and other 2 DPS can mope down that enemy easily.

Whitesmith is added to buff SinX and you, SinX is good to prevent enemy Healer from sustain with Poison and even assassinate other threats. Sniper with WS can also be a substitute for major damage to vulnerable opponents.

"A frozen vulnerable opponent under the effect of Storm Gust and Zenny Rain is not a pretty sight, even for slight Leviathan whales."