also wondering if anyone knows what kind of sentences these offences normally get
WARNING - this post MAY be triggering but I have tried to write it in such a way that it isn't.
It largely depends on exactly what was done and how often. It also depends if your daughter and sister were over or under the age of 13 at the time.
I obviously won't go into detail as - believe me - I can empathise with you. The starting point for the very mildest thing would be 12 months if she was over 13 or 2 years if under 13.
The sentences get progressively more severe depending on what has happened. Going up to 15 years for the worst cases.
There are also what are called ''aggravating factors'' and ''mitigating factors''. Any aggravating factors would lead to a longer sentence on top of the figures given above. So, for example, the fact that there were multiple victims would be an aggravating factor as would multiple offences over an extended period. Also, the age difference is also taken into account. Eg, a grandfather is treated much more harshly than, say, a 15 year old boy would be.
In the case of your sister, as this is - presumably - a historic case, he would be treated under the law as it was at the time that the offences took place. You should be aware that even ten years ago the sentencing guidelines were for a lot shorter sentences than they are nowadays.
Do be aware that whatever sentence he receives, he will then be released on licence when he has completed 50% of it. So, for a 5 year sentence he will be released after 2 1/2 years and spend the remaining 2 1/2 years on probation.
However, having said that, since this is a sexual offence the probation service will place very severe restrictions on what he is allowed to do, where he can go and who he can talk to. He will also be made the subject of a Sexual Offences Prevention Order - SOPO - that will place VERY severe restrictions on him and he will have the police checking up on him regularly.
Hope this helps and it didn't cause any upsets to anybody