Not recent but have just located the link to the European Court hearing on two cohabiting sisters.
An interesting case which has hit the UK media see also here.
The Court ruled narrowly in favour of the Government but the case may proceed to the full European Court for a final hearing.
In essence it seems to be that since Civil Partnerships were introduced for same sex couples it is in some way discriminatory not to extend protections to everyone including unmarried straight couples and co-habiting siblings and other relatives.
It's a bit confusing because prior to Civil Partnership there was a big hue and cry over the need to reserve certain benefits to 'marriage' but since gay people got in on the act you need to dilute it as much as possible to prevent same sex couples feeling they are being equated to marriage.
Well it's confusing, because although the logic is decidedly iffy (especially as the Daily Mail reporting of it has a distinctly homophobic edge to it, as though Civil Partnerships created the problem), there is a very strong case for ensuring protections are available to de facto couples (common law spouses etc) as well as various other combinations - especially as regards the disposal of property, inheristance tax and so on.
The reason (so far as I can see) for the Government reforming family law in bits at a time is simply to try to avoid a massive mobilisation by the religious right about diluting marriage and so on. At the moment those voices are tending to argue that siblings who share a house should be protected.
This is a good development, though it certainly does tend to undermine the traditional view of marriage and recognising that non-married partners as well as friends and relatives may share their lives and/or property with someone and that should be recognised by the State.
Of course there is always the danger of tax avoidance, especially in the case of inheritance tax. I'm not sure I'd be in favour of certain people being able to make a declaration about living in the same property and then avoiding paying taxes, whereas others wouldn't - that wouldn't be fair, but it's certainly something the Government should look into.
If the ECHR develops its thinking any further they may have little choice and the media coverage tends to suggest that there is a broader support for all cohabiting couples including (genuine) cohabiting siblings.
For information on Law Commission proposals relating to cohabitation see here and on the Law Commission consultation website.