Sue..I dont know if this is any help for your Dad....

You cand get "Fortisip" from the doctor ...it comes in a drink form a bit like a milk shake but in lots of flavours...

 

Also there is a powder that you can put in anything food or drink it is coulorless and tasteless and it just adds calouries to help build him up..

It is very good stuff I had to use it untill i learnt to swallow ..

Your Dad could use this as a meal replace,ent it he wishes

 

Hope that is of some help....