Divine Ruination (aka Holy Explosion) is the preferred chaining move because it does not have an overlap when dual wielding and the unit is static so chaining is easy and reliable.

The frames are 70-7-5-7-7-7-7

Christine Ice Shards are 49-7-7-7-7-5-7-7-7-7. Barusa carpet bomb is 49-7-7-7-7-5-7-7-7-7.

These both work out to be 70-7-5-7-7-7-7, where 70=49 7 7 7

So Christine, Barusa and anyone given ice shards by Christine can chain the first wield with the Divine Ruination family.

Barusa can equip Breath of the Rose for dark element chaining with DV. This reaches the chain cap.

This should allow Christine to be a weak finisher with only one other member of the Orladeau family.

Edit: carpet bomb is activated by equipping Grasping Sphere shield.

Christine LB would make Barusa element chain with DR too. Christine could alternate LB with damage to provide max chain from Carpet Bomb/Divine Ruination without Ice Shards.

TL:DR Christine and Barusa can spark chain with Orlandeau family Divine Ruination. Christine can give the ability to anyone. Just start them at the same time.