Can Siberian Peashrub be grafted with another legume like pigeonpea?

Hi, I'm planning to give a shot with some perennial nitrogen fixing tree/shrub legumes. I found three options: chachafruto, pigeonpea and Siberian peashrub. The first is practically impossible to have for me, while pigeonpea would be nice, it is short lived. Since Siberian peashrub has a long lifespan, it would be perfect, but I'm really scared about its potential invasiveness (I live in a natural protected area and I don't want to ruin it), so I'm searching for the possibility of grafting a non invasive relative on its rootstock. Could pigeopea do the work? And sorry for the silly question, but what about other legumes? Could also be possible to graft a winged bean or a fava bean on a legume tree/shrub like Siberian peashrub? I found another topic with this question but it is not conclusive.

PS: I live in the South of Italy, on the coast, and here the equivalent USDA hardiness zone should be 10, but I see that here people are able to grow even trees of really different climate, so I would even try experimenting with strange mixes in my orchard.

Thanks

Lets say that pigeon pea last 4yrs in your environment, and siberian peashrub last 20yrs.
If you graft the 4yrs to death pigeon pea to the siberian peashrub. The pigeon pea will still die in 4yrs.

I also think that pigeon pea roots are better than siberian peashrub, they fix more nitrogen and the unlock more phosphates.

There are dozens of long lived nitrogen fixers that are native/naturalized in your area, why did you select siberian peashrub over them?

All that said, I do think that it would be pretty cool for you to try grafting different legumes and let us know which grafts are compatible.

Hi, thank you very much for the reply. They are not the only nitrogen fixers that I want to use, also they attract me more for the high protein, low perishable fruits. I'd like to use, just for fun, different design combination, some high carbs tree like chestnut, moringa and breadnut, some high fat tree like macadamia, almond and hazelnut, but it seems to me that growing high protein beans on trees has limited options compared to the others, so I'm searching for some tree/shrub that can live for a lot of years, that give me high protein edible and non perishable seeds, and that can fix nitrogen as a bonus. It is just a little design obsession that I have in the last few weeks 😛 we have carbs trees options, fat trees options, but where are protein trees options?

Yes I can try with grafting and give an update, but I'm not a very practical person, so it could take me a lot of time to make these experiments and I'm asking just in case some people more informed or more practical than me could already have the answer.

Anyway, thanks for the explanation on grafting and lifespan, I'm asking because I see here some people grafting solanaceae like omatoes and eggplants on more resistant rootstock in order to increase their lifespan, so I have assumed that selecting a high lifespan rootstock could dictate the lifespan of the grafted plant.

Hazelnut is actually a very high protein produce. It actually has twice the amount of kidney beans:
Beans: https://nutritiondata.self.com/facts/legumes-and-legume-products/4297/2
Hazelnut: https://nutritiondata.self.com/facts/nut-and-seed-products/3116/2

I have seen labor intensive ways of preparing tamarind seed.
Roast...De-shelling....Soaking/Fermenting....Recooked or eaten with specific food.

The pigeon pea can self seed, especially in your environment, so keep an eye on them as well.