Leeds confirmed on Monday evening that they had signed both McKay's, just days after snapping up Middlesbrough winger Mustapha Carayol until the end of the season.
The 19-year-old twins were born in Glasgow but joined Doncaster at a young age, and have been tipped for a bright future recently, hence the interest in their signatures.
Paul is a tall centre back, whilst striker Jack - also standing at 6ft 3in - will be seen as a targeting man, possessing strength and aerial ability to lead the line.
Now, both players will be looking to make a big impact at Elland Road in years to come, but a report has now revealed how close they were to signing for West Ham United instead.
The Yorkshire Evening Post report that West Ham had struck an agreement to sign both players, and they looked set to join the development squad at Upton Park.
However, Leeds hijacked the deal on Monday, paying a nominal fee to local rivals Doncaster and beating a Premier League side to two promising signings in the process.
That's a major coup for Leeds, and shows the pulling power of the Elland Road club despite being in the Championship - and manager Steve Evans will be hoping that his faith in the two young players will be repaid in the coming years, given that both teenagers have the potential to become first-team players.