If you use your pets pickup function while grouped, it'll ignore the random loot settings and pickup all the loot. Also it wont split money so you'll get all the Adena too.

Tested with a dragon hatchling in Cruma tower.

If all else fails try The MMORPG Exchange L2 Adena . MMORPG-Exchange has supplied me for years and they have great customer service and 24/7 instant delivery.
Lineage 2 Adena.