  Voter control problems model situations in which an external agent tries
toaffect the result of an election by adding or deleting the fewest number of
voters. The goal of the agent is to make a specific candidate either win
(\emph{constructive} control) or lose (\emph{destructive} control) the
election. We study the constructive and destructive voter control problems
whenadding and deleting voters have a \emph{combinatorial flavor}: If we add
(resp.\ delete) a voter~$v$, we also add (resp.\ delete) a bundle~$\kappa(v) $
of voters that are associated with~$v$. While the bundle~$\kappa(v)$ may have
more than one voter, a voter may also be associated with more than one voter.
We analyze the computational complexity of the four voter control problems for
the Plurality rule. We obtain that, in general, making a candidate lose is
computationally easier than making her win. In particular, if the bundling
relation is symmetric (i.e.\ $\forall w\colon w \in \kappa(v) \Leftrightarrow v
\in \kappa(w) $), and if each voter has at most two voters associated with him,
then destructive control is polynomial-time solvable while the constructive
variant remains $\NP$-hard. Even if the bundles are disjoint (i.e.\ $\forall
w\colon w \in \kappa(v) \Leftrightarrow \kappa(v) = \kappa(w) $), the
constructive problem variants remain intractable. Finally, the minimization
variant of constructive control by adding voters does not admit an efficient
approximation algorithm, unless P=NP.
