Non-extended and extended SUSY 
*

*What are the distinctions between Non-extended SUSY and Extended SUSY?

(Is that just a non-extended SUSY has $\mathcal{N}=1$ while the extended SUSY has $\mathcal{N}>1$ ? Then there is no conceptual upgrade?)
2.

*

*If we start from a non-extended SUSY, how to obtain an extended SUSY?


*If we start from  an extended SUSY , how to obtain a non-extended SUSY?
(via SUSY breaking? what else?)
 A: *

*One can get extended SUSY by combining two supersymmetric multiplets into one with the appropriate choice of coupling constant. For example - in order to get $\mathcal{N} = 2$ SYM (Super Yang-Mills) one combines the gauge multiplet with gluon $A_\mu$ and gluino $\lambda_\alpha$ with the chiral multiplet with a fermion $\psi_\alpha$ and a scalar  $\phi$, all fields in the adjoint representation of the gauge group.
\begin{gather*} 
A_\mu \\
\lambda \qquad \psi \\
\phi
\end{gather*}

*Yes, one can "downgrade" the SUSY by symmetry breaking - for example in the famous artice by E.Witten and N.Seiberg "Monopole Condensation, And Confinement In N=2 Supersymmetric Yang-Mills Theory" https://arxiv.org/abs/hep-th/9407087 - SUSY is broken from $\mathcal{N} = 2$ to $\mathcal{N} = 1$ by the superpotential term :
$$
W = m \text{Tr} \  \Phi^2
$$
And this breaking is crucial for the monopole condensation and the description of confinement. I am not aware, unfortunately, of the other mechanisms of getting a symmetry with less SUSY in other way than the symmetry breaking by introducing soft or hard SUSY breaking terms or spontaneous SUSY breaking.

