Consider there is a transmitter at A and receiver at B and transmitter is transmitting radio waves. Further there are obstacles of different sizes in between A and B. Now if we increase the frequency of operation will there be more reflections in B. This assumption comes form the fact that for smaller frequencies some obstacles may not reflect to B.
Many aspects of a transmitter to receiver path change with frequency.
The first and most obvious is the size of the Fresnel Zone between them. This will affect how many obstacles need to be considered as being 'near' the transmission path.
For objects whose size is comparable to the wavelength, there may be resonance effects which change the reflection of that object strongly with change of frequency.
The path difference between off-axis reflectors and the on-axis main beam will vary with changing frequency.
The situation is so complex when there are obstacles that links are usually set up so the Fresnel zone is clear of them. When there is significant obstruction, measurement is necessary to assess the range of link conditions that will be experienced, no operator would accept such a link based on modelling alone.