Rus,
I really don't think that there are a lot of children from conservative Christian households who doubt that conservative Christian culture thinks homosexuality is immoral or contrary to God's plan. Even with the use of post-modern terms, the message seems to have gotten through loud and clear. The problem isn't the terminology, it runs deeper into the sociological changes wrought by post-modernity and globalization. Insisting on not calling homosexual couples a "family" isn't going to turn the tide, it just makes us look like jerks.
The use of the terminology you so strongly argue against may communicate that society at large views such-and-such as normative, but children are remarkably perceptive. They pick up rather effectively what their parents and church believe about things (even the attitudes and dispositions we'd rather they not pick up).
Inevitably, two things will be true for most children in Christian families: they will be aware of what the Church teaches about same sex unions, and aware that the Church (in America) stands against the trajectory of "mainstream" society.
From there, they'll have to make a choice. We all, ultimately, have to make a choice.
In the end, regardless of what language we use to describe things, our kids will have to make a decision. By the time they are ready to do that, they are old enough to have had a longer conversation on the subject (a conversation which we, as parents, should be pro-active in pursuing); and the longer the conversation, the less important it is that a particular word is used or not used. Refusing to call same sex unions a "family" or demanding the use of the term "sodomy" rather than "homosexuality" will not, in an extended conversation or over the course of someone's lifetime, stop them from understanding that society views homosexual families differently from Christians.
I honestly think it makes no difference. If anything, the intentional use of such negative language sets the Christian up as someone trying to "poison the well," - it makes us look judgmental and bigoted. I would rather utilize the mainstream terminology, and have a long enough conversation to get to the point that terminological problems fade in significance.
It ultimately doesn't matter if you call a red rose "blue" if you have a long enough time to explain that, when you say "blue" what you mean is what society calls "red."