Disposal Account in Consolidation

Guys i have a confusion..
1st. What is the difference between Group Point of View and Parents Point of view in consolidation.

2nd. I noticed that in Consolidation, in case of disposal when status is changed eg from 70% to 10% , sometimes we take Cost of investment at debit side of T account and sometimes its net assets..
For example in Question Grange we take net assets while at some places its cost of investment.

why there are two different treatments. and when to use which treatment.

please help me. I am very confused about this.