I'm trying to draw a tree using the forest package, and while I've got the architecture of the basic tree down, I'm having some trouble drawing arrows and circles. My tree is generated from:

\begin{forest}
[DP[][D'[la][DemP[][Dem'[sa][PlP[][Pl'[yo][NP[liv]]]]]]]]
\end{forest}

I'd like to 1) draw an arrow from the NP node to the PlP node to the DemP node 2) draw a circle around the entire tree from DemP to NP and 3) draw an arrow from the circle to the DP node. Any advice?

FWIW I also have other tree packages installed, so if someone could explain the process using another package, I'd be fine with that. I'm using the LyX editor, but am using TeX code for these trees. Thanks!