How to Estimate Carrier Frequency & Amplitude for Several Overlapped Template Signal
If the auto correlation of the signal is sharp enough, you can do Matched Filter and search for local extreme points.  

Yet it seems the figure you'e displaying is in the frequency domain.
But we can treat the frequency domain as it was time domain and work with the same "Trick".

Namely searching for the frequency in the frequency is like searching for the delay in the time domain.
Since the signal is known, its multiplication by a carrier is known whihc will be used as the Matched Filter.
Applying it will yield 3 peaks each with its own "Delay" which corresponds to its frequency.
Going back to that frequency bin (Or calculating the DTFT at that point) will yield the amplitude.