the only issue i see is how you develop your friendship with your neighbor ..... you have to live there for a long time ... and you better do it right ....

second issue first... you cant force them to remove a tree on their property .... unless you are willing to pay .. and talk them into it ....

and in regard to the property line.. boy this is a nightmare in the making if done improperly .... anything on your side of the line.. and you better be right ... is your to do with as it pleases you .. in other words.. get it off your garage .... but as for digging it up ... well that's where good neighbors come to agreements.. perhaps.. split the cost.. or the work.. etc ...

bad neighbors will fight you ...

indifferent neighbors will say they don't care.. but wont help ...

do you see where the problem isn't the plants.. but your relationship with the neighbor ...

until you define that.. it doesn't matter if they can be replaced with a given plant ... we can handle that later ... firstly .. work on the relationship.. then remove it.. then come back to us and we will help define what to plant there ...

good luck ... ken