It would be far cheaper and better for your gg to go and buy another horse to keep it company - an alpaca is not a horse substitute at all!! They are also very expensive depending on the quality of their wool and the colour - they can range from £1000 to £9000 for one adult!!!
They also need shearing twice a year which means you need a specialist shearer and a crush for them to flip them on their side for shearing - it is very stressful for them, add lib hay all year round to help maintain their specialist digestive system, sparse grazing, they spit!, they are more sensitive than sheep so die/go lame at the drop of a hat, they don't cope with very wet ground, they need their hooves trimming every 8 weeks so will need to be flipped for that if you have not trained them to pick up feet - not easy with an animal with a brain the size of a peanut that also means halter training them first!! They need access to shelter and males need to be kept separate from other males as their main aim in life is to castrate, with their large canines, their opponents or any threat! - not really for the faint hearted or a cheaper horse alternative!!
They also won't play with your youngster so could get some serious injuries from a boisterous baby as they are not very big or as heavy compared to a horse or pony!
Horses need other horses for company especially whilst growing up - you could use another grazing animal as a very temporary companion for a calm very secure adult horse, but personally I wouldn't as I've had youngsters kill 2 of my sheep in the past - they make great fluffy footballs apparently!!!!!!