It wasn't only the Dober Family who tried to snatch the sacred guardian from Ainsley. Even the other 6 families had the same thought.
Only the Raos Family and the Ale Family held back their desire. As the family with the highest intel agent, they were more cautious than others. Not to mention that the Raos family was the most loyal one out of the other families.
The Ale and The Chale family also didn't do anything much other than gathering information since they didn't have the power to offend the main family like the other branches.
To openly or secretly steal the sacred guardian from the main family was like a rebellion, and that wouldn't end good. That's why the branch families all resort to using the trickery tactic first, before using force.
Of course, when they used force, they would use disposable pawns and easily put all the blame on these pawns, saving their families from the Sloan Family's wrath.