If I have two transfer functions in series G1(s) and G2(s) where G3(s) = G1(s)*G2(s), I know that following holds true:

-for any given frequency, the magnitude in dBs of G3(s) is equal to the sum of the magnitude of G1(s) and the magnitude of G2(s)

-for any given frequency, the phase of G3(s) is equal to the sum of the phase of G1(s) and the phase of G2(s)

If instead G1(s) and G2(s) are connected in parallel where G3(s) = G1(s)+G2(s), is there any such shortcut for determining the magnitude and phase of G3(s) at a given frequency based on the magnitude and phase of G1(s) and G2(s) at that frequency?

Thanks,

Kevin