Oscilloscope modification to make more wide bandwidth is a stupid idea. This is because oscilloscope frontend bandwidth is designed to fit with Nyquist border of ADC which is a half of sample rate. So if you extend frontend bandwidth, but keep the same sample rate, you will get more aliases and as result oscilloscope will be unable to show proper waveform for a complex signal which consists high frequency components.
Due to physical limitations of analog filters, there is a rule of thumb to use sample rate at least 10x times higher than required bandwidth. And since DSO2D15 has sample rate 1000 MHz, you're needs to limit input bandwidth to 1000/10 = 100 MHz. If you use more wide analog bandwidth your oscilloscope will suffers from aliasing issues.
Oscilloscope frontend modification to extend analog bandwidth from 100 MHz to 200 MHz may have sense if you're planning to use it to measure amplitude. But note that with such kind modification you cannot believe to waveform displayed on oscilloscope.
Such modification just make your oscilloscope defective and it cannot be used as a usual oscilloscope to check signal waveforms.
There is more sense to reduce analog bandwidth from 100 MHz to 10-20 MHz. It will give you some benefits, like lower noise and less waveform distortions. But usually oscilloscope already has a switch in the menu to reduce bandwidth, so there is no needs to "hack" it to get that benefits.