Law Firm Politics. Advice needed

So about a month or so ago i became part of senior management and became head of 2 branches of my firm.

The reason behind this was because i went from a normal associate to running one of the offices because the Solicitor in charge had left. I started managing the team and long story short i had taken the office out of the red and into the black.

I was then tasked with doing the same for another office which is local to me. I had taken over the office, hired more staff then for the first time had broken even with enough fee earners to support growth within the firm.

I did what was asked of me and i do like the firm i represent and want it to do well. But there is one particular BDM (Business Development Manager) who keeps overstepping her role and undermining me, loudly questioning my decisions and arguing/debating with me, going above me to my bosses whom she has a separate rapport with.

I at first took her under my wing when she first started. I showed her leads to go after as she was new to the role. Which leads to follow, which panels to go after, which people to talk to. Even putting her in touch with my personal connections who brought work to the firm. I helped her because she came to me asking for my help and my mindset was ‘we are a team lets do this together’ so i even sat with her in meetings often covering her back when she didn’t know NOTHING about what she was talking about.

My boss, the owner of the firm said to me ‘if there is a problem or any issues please let me know directly’ only issue is he doesnt respond to my messages, calls or texts. Only hers, i get no responses or support from above me.The managing partner shares my sentiments and agrees with what ive said as he sees it himself yet nothing has been done. Dismissing people is the last tool in my arsenal but in this case i need her to back away and focus on BD not office management

Ive advised as BDs i propose all BDs be out on the field to find more work as we have had some work but we have BDs in the office and acting like they are office managers now often overstepping on my teams respectively. For example. An employee has a fully remote contract but she comes in to help us out of the goodness of her own heart and she runs her files perfectly and bills nicely. Now decides to work from home and yet this BD is coming to my office shouting at me demanding answers why this said employee is working from home. Another example is this same BD is saying my boss is asking me to hire more solicitors, again till my boss says it to me directly i am not doing anything. Then this BD is also going to people in my team asking then what they think of my leadership and trying to get them to come forward and criticise me. Each of the members in my teams have all came forward to me immediately and told me what was said.

The issue i have here is this BD is a thorn in my side, i dont want to boss anyone around but the undermining of my authority and running of a team is becoming an issue and im unsure how to deal with it when management say they are doing stuff and nothing happens.

I was a consultant prior to joining my firm permanently. At this rate im inclined to dump both offices and go back to consultancy.