How to pay my portion of property taxes only and get credit

[Bharath Raj]

I bought a portion of a commercial property (I own 5100 sq ft detached building while the original owner owns 16550 in 5/2017. At closing, I received a credit for pro rata estimated property taxes for 2017. Harris county (Houston) sent the tax bill for the entire property to the previous owner. The owner is invoicing me for the property taxes and wants me to pay him by mid december (tax bill is due by the end of january 2018). What is the best way to approach this? If I call the tax office, will they separate out the bill? How can I get credit for paying property taxes, if the previous owner makes claim to the whole tax bill? Is there anything else I need to watch out for? 

I appreciate your responses