While expanding scope is a popular TrollingTactic, this behaviour might be indicative of a stalker (cf. WhatIsaStalker). Being first to take an online conflict offline will expose you to serious liability in this case. If at all possible, never be the first one to ExpandScope. Once a conflict with a stranger expands outside the limited scope of an OnlineCommunity, call the police. But we recommend avoiding the police until you cannot get away from the person, since a bench warrant or restraining order only works after the fact, and the acquisition of said warrant or order will give away too much of your personal information to the stalker.
Expanding scope often is tempting since it feels like it might give you an edge in the conflict since it might demonstrate "overwhelming force" and thus allow you to win. In a sense, it offers to recan the worms with a bigger can. In practice, all it does is make things worse by expanding the ConflictCycle. Further, it may bring in more parties, which means there are now many more relationships in tension that will have to individually undergo ConflictResolution.
Never be the first to expand scope. If you have unwittingly do this, seek to reduce scope as quickly as possible before you ratchet the conflict beyond a point you cannot pull back from.
Conversely, see LimitScope.
Example: Wikipedia's WikiPedia:Wikipedia:request_for_comment works on the premise that expanding scope by getting comments from other people in the community is good for solving disputes. I think that this works if the community is roughly in agreement over the matter: the community can beat down minority opinions with weight of numbers (which is bad, because it enforces GroupThink, but it does resolve the dispute). However, if the CommunityDoesNotAgree, this escalates a dispute between two people with a strong interest in some particular matter, into a dispute between lots of people, each of whom has a weak interest in the matter (c.f. ConflictParadox). This is probably not an improvement.
In general, ScopeManagement is among the most important political techniques. Different groups have varying influence depending on scope, therefore they seek to manage the scope to maximize their influence.