Forgive me for this, but I do not quite understand why you are SO SO desperate to find his original medals. Yes, I agree that it would be very nice to have them.
My grandfather died in WW1, leaving a widow and only daughter. When my parents died, I, as the only child, inherited everything. In a box of jewellery I found one broken medal - he was awarded two (British War medal and Victory medal). Rather than just throw it away, my instinct was to have the broken medal repaired and refurbished, and I then found that I could buy a replica medal for the missing item, which I did, along with a replica WW1 Memorial Scroll. I am more than happy with that solution.