Complex sentence: Firstly, the age range was altered to cater for those young people aged 18 to 25 years, largely to ensure that the Scout sections tie in to other organisations, such as the Duke of Edinburgh's Award programme.
Split into simpler sentences: Firstly, the age range was altered to cater for those young people aged 18 to 25 years. This was the first time that the youth sections in Scouting extended up to age 25-this was largely to ensure that the Scout sections tie in to other organisations, such as the Duke of Edinburgh's Award programme.