Please check this post where a colleague exemplary provided a suitable solution.
For the sake of completeness, please note that we don't provide technical support for PRTG customization, no matter if the customization relates to PRTG Maps or PRTG Reports. The reason for us to decline such requests is based on the amount of time it usually takes to troubleshoot those requests that mostly affect only a few or sometimes just one single PRTG user.
Further information can be found here:
What is your position towards customizing the PRTG web interface?
Birk Guttmann, Tech Support Team