In New Zealand's flavour of Mixed Member Proportional Representation, the Sainte-Laguë method is used to determine the total number of seats a party gets. These seats are allocated to the electorate winners first before going down the party list.
Imagine if a hypothetical Sketchy Party wishes only to nominate a party list, and not nominate any candidates in electorates. However, they wish to informally support a number of independent candidates who are friendly to the party. If any of these independent candidates win, they would become overhang seats, and (assuming they get more than 5% of the party vote) the Sketchy Party would effectively get more seats than Sainte-Laguë would entitle them to.
Is there anything either in the general principles of MMP, or the specific rules in New Zealand, that would prevent the Sketchy Party from being able to exploit such a possible loophole?