Moving from HA property due to demolition - what are the tenants rights?

[TidyDancer]

Bare with me if you will, as this might be long! i will try to be as succinct as possible!

My aunt is living in a housing association property that she has been in for approx 15 years (could be a little bit more). She lives with her two adult children, they are 25 and 26. My aunt is retired and my two cousins work full time but in low paid jobs (not quite minimum wage, but the equivalent of a couple of thousand each above that on a yearly basis). The town they live in (Home Counties) is very expensive to rent or buy privately, and neither of them are in a position to afford it. There are very very few private rentals in the area, most people own or rent from three or four housing associations who have properties in the town. There are no council properties, they were all sold to housing associations years ago.

According to my cousin, there have been rumours for some time that they will be doing a mass demolition of properties in the area (the area being one very long road with some courts and closes off of it). The make up of the properties are a mixture of maisonettes and flats, comprising over 100 individual dwellings, maybe as many as 200, my cousin wasn't sure. The rumours affect all the properties.

In summation, all properties are likely to be demolished and rebuilt in some way and my cousins and aunt are worried about their rights. I'll list a couple of crucial points:

*my aunt has a secure tenancy and is concerned that if she and my cousins have to move out that they will only be offered a short term one (I think they are 5-year tenancies, but I'm not well versed in that area). Does she have the right to keep the conditions of her existing tenancy when she moves? And then moves back (as they are being led to believe they will be able to)?

*what rights do my aunt and cousins have to an equivalent property? Because my cousins are adults, will they be taken into account when it is decided what type of property my aunt (as the tenant) will be moved to? They really can't afford to move out around the area they live in and they want to live together anyway. They are currently in a 3 bed maisonette with their own entrance and small private garden. Can they request (and should they be given) an equivalent property? In the town, there are no other maisonettes that they could think of that have that specification. The most obvious answer would be to offer them a house as it has all the same specifications, but would the HA have a right to move them to a smaller 2 bed property instead (as there are maisonettes and flats that are 2 bed properties)? The HAs in the area have a policy (not sure if official or not) and history of giving houses with gardens to families with children. There have been some exceptions, but not many. In my mind, this would be a circumstance that warranted an exception but they may not think the same way.

If anyone could answer these queries, I would be very grateful, as my aunt and cousins are worried. I don't want them to be panicking about this. They are going to a mass meeting with the HA this week and may find out more info, but if there is anything anyone can advise it would be very much appreciated.

TIA. :)