Need help winning a multi-family deal in Houston

[Kusum Chanrai]

Hello! I'm trying to buy a multi-family apartment building in Houston. I'm facing two challenges: 

1) Incentives are not aligned in my favor. The deal is through Marcus and Milichap. I'm working with 1 broker from San Antonio, but that is not the Seller's broker. The Seller's broker in Houston also has a client who I'm competing with. He would obviously much prefer it to go through him, so he gets twice as much commission. Has anyone encountered a situation like this? If so, do you have any advice for me? Can I ask my broker if he'd hand the deal over to the other broker - and I'd pay him on the side? 

2) I've just offered asking price for the property. It will give me a 8% Cap Rate. It might need to go above asking price. I'm thinking of offering up to a cap rate of 7.5%. How does one decide what price to offer up to? 

Any advice or suggestions would be much appreciated.