Soon slips/Link trains will be no more in Indian Railways
The concept of slip/link trains is actually good as it helps to reduce rakes and maintenance times
For example, A train need to go Jammu Tawi from Howrah via lko
But also need to go New Delhi
So...
more... a slip train will be detached at DDU and will be send to Jammu Tawi via BSB-LKO and the full train will continue to go New Delhi
But LHB generator car is the main problem
So IR can/should introduce a connecting train which will halts till it's connecting train comes and people boards that train
This will not require any extra arrangements like attaching/deattaching
And more destinations can be connected to one train