The characteristic impedance will definitely change, that's not a microstripline, that's a signal bus.
In order to preserve the impedance characteristics, (which you don't really need in this case) you'd need to use a divider/combiner to maintain the match. Losses will be...high.
In your case, for a receive circuit like this matching the impedances is not a big deal unless you need to sqeeze the last few dB of signal out of the noise, and at 10-200Mhz bandwidth, maintaining that impedance match for weak signals is not the biggest worry.