Push current source through transfromer
Think of a KCL at output + node. You have three currents summing up to build secondary current (generator, capacitor and load), say
\$i_\text{sec}=i_\text{G}+i_\text{C}+i_\text{R}\$.

Now I guess you would be happy do move this secondary current to the primary side
\$i_\text{pri}=i_\text{sec}/D^\prime=(i_\text{G}+i_\text{C}+i_\text{R})/D^\prime\$ 

But with some simple algebra (division is distributive) you can now move each of the individual currents left or right the transformer

\$i_\text{pri}=\underbrace{i_\text{G}/D^\prime}_\text{generator moved to the left}+\underbrace{(i_\text{C}+i_\text{R})}_\text{R/C on the right}/\underbrace{D^\prime}_\text{moved to the left}\$