Perfect, I made some changes to fix via dell'Agricoltura: changeset/177036602

Everithing seems correct, further refinements need further surveys. But the situation for me is now more than acceptable.

Thanks for your precious help, without help I would not have been able to do it.

Via dell'agricoltura doesn't cross SP2 Var. No road crosses SP2 Var, except the cycle path that I created near the northern roundabot.
If you can move ciclabile valchiavenna relation on the new path i can correct via dell'agricoltura myself.
Anyway I'll try to explain. Via dell'Agricoltura now starts from via Zocchi here way/1465429398 then runs next to the SP2 Var like this way/1465429406 .

This way/1465503107 still exists but it's not connected with the new via dell'Agricoltura.

For this way/1465429402, if I undestood, is correct what you say, but I'm not able at all to work with relations.
This way/1465429406 shoudn't be part of the Ciclabile Valchiavenna relation.
Instead this way/1465429402 is part of Ciclabile Valchiavenna.
Pista ciclabile Cristoforo Colombo is a name like via Giumello (name of the road) in Novate Mezzola that is also part of the relation Ciclabile Valchiavenna.

I'm impatient so I had another drive (waiting for a bike survey). Now I have new informations and a new gpx. So i made a new edit. Maybe you can help me again. changeset/177003407

I also don't understand how should I mark the structure:
pista ciclabile is on top of the embankment, but also the track is on top of the embankmente but on a lower height. Maybe is wrong "two_sided" for both road.

Now I don't have yet informations about what they did with this, so I left it as it was even if now it's wrong.
way/88222071

I need to move via dell'Agricoltura on the east side of the SP2 Var. But not the beginnig and the end: there are new beginning and new end, I just created them. Problem: Ciclabile Valchiavenna relation/6588150#map=14/46.18402/9.43820&layers=G now runs on top of the embankment, no longer on via dell'Agricoltura. At this moment I'm not able to move this.

Yes, it is correct. Whith future gpx tracks I'll check precisely via Italia.

way/293960024#map=19/46.263594/9.391995 this road now runs next to the new road sp2 var on the east side. It is the new via dell'Agricoltura. But they changed a bit the intersection.

I'm a begineer so I haven't learned jsom yet. Also I'm not familiar with forum or "support chat".

Unfortunately I only have that gpx file. I recorded it via car, now I can't go to this place to record further tracks, but as soon as possible I want to go there by bike. The track only contains the new car road.

On the north the new roundabot is contained partially. I didn't remember to have a full loop around. But the track contains it, and via Italia is now straight and goes into the roundabot. The older intersection no longer exists.

Yes, you found the correct relation. I think that it shoud stay on the old road. The new road have another number (SP2 Var) on the road signs. So until the Provincia doesn't change something the new road isn't part of this relation.
The problem is that I can't cut the old road to insert the roudabot... I'm afraid to break something bigger.

For the same reason I didn't correct via dell'Agricoltura. It is part of Ciclabile Valchiavenna relation/6588150#map=14/46.18402/9.43820&layers=G
I'm pretty sure that now it isn't. This path (ciclabile valchiavenna) runs on the track that runs next to it on the west side. There's no any road between the new SP2 Var and the track on the river bank.
Via dell'agricoltura now runs on a new route on the east side of the SP2 Var.

Thank you for your help. I hope I wrote in an understandable way.

In the reality the road is connected through a roundabout in the North. I had to understand how to modify via Trivulzia and via Europa. They are part of a path. I had to cut that road to add the roundabot: how can i do that?
The same problem on the old road via dell'agricoltura. For the most part it runs on a new track on the east side of the new sp2 var. But I have to cut it bucause at North and at South is in part on the west side. Problem this road is part of the path ciclabile valchiavenna. So I can't cut it.
Also as I saw it was a wrong information because I saw people walking on the embankment: so the correct path of ciclabile valchiavenna is the existing track, the nearest to the Mera. I also saw the north access and it is the only possible way it can be. You can check the gpx file to see that i traveled the new sp2 var. Can you help me? If you can at least help me to understand how I can modify the two path I would be grateful.

Ciao, nel tratto da te indicato (ad est della SP4 dirA) c'é solo un percorso del Sentiero Valtellina. E' così da molti anni, corre sopra l'argine ed è asfaltato. Non mi risulta essere affiancato da altre stradine/sentieri, certamente non c'è nient'altro con asfalto.
Non ricordo più com'era la situazione quando ho fatto la modifica, ricordo solo che avevo aggiunto dei tratti mancanti della pista ciclopedonale.