It has been said that if you want to get rid of an enemy, then give him a smallholding. The theory being presumably that running a smallholding is likely to use up most of his time and money and therefore he will no longer be a nuisance to you.
You have asked a somewhat open question country soul. What exactly did you have in mind? Are you wanting someone to help buy the extra sheep you will need to fill the extra land?
Do you want someone with experience to help you with lambing?
Or are you looking for someone with no experience to help you at peak times, for little or no money as they will be gaining experience as they go along?
I have, in the past, had someone help me with fencing, foot trimming etc as he wanted to gain experience. He was more trouble than he was worth as appeared to have little natural ability and it took me longer to supervise and redo what he'd done wrong than if I'd done it myself in the first place.
I also had a sort of partnership with a neighbour many years ago. We owned a couple of acres of land each and decided to get a few Ryeland sheep, and share the care of them. We got them home and I trimmed their feet as they'd been a bit neglected. He was going to do the next trim. It never happened. I also gave them their initial vaccination and he was going to do the second one. That also never happened. I wormed them all, and for some of them that was the last time they were wormed as by then I could see how this was panning out, so suggested that we separate them and each look after his own. Even that involved me alone as I had a sheep dog and a decent trailer and he didn't. But it wouldn't have been insurmountable for him to have at least been present at the gathering to open and close the field gates, if nothing else. But he had to go shopping at that exact time - even though he was retired and could have gone any time.
So my personal experiences of any sort of partnership are not good.
But all circumstances and people are different, and you can never say "never".
However, I am mindful of some advice I was given many years ago which is "The worse ship in the world is a partnership." Obviously not always true, but like in any relationship, it's easy to get a long way in before you realise you have chosen the wrong person, and then it is difficult and stressful getting free again.