Hey there @hossamzaio! Welcome to the community! Are the splines you’re intending to connect procedural/determined at runtime? Or are they put together in editor? If in editor, you can just overlap the portions and have the same node locations on each. At runtime, the idea would basically be the same, but if it’s a spline mesh that you want to blend, that gets significantly trickier.
A quick thread with 2 excellent resources for working with splines at runtime (or in general for the Epic tutorial):
Hi, another option is rdSplineTools - it allows you to break up a spline into smaller sub-splines - you can just copy/paste your existing train track spline (or just the spline data itself using rdSplineTools) and then break it into X amount of sub-splines which you can then use however you wish.
https://www.unrealengine.com/marketplace/en-US/product/rdsplinetools
If its in editor, you can also store all the splines that the track should follow in an array. Then in blueprint do a for each loop on this array and get all spline point locations and tangents for each spline and store this in a array’s. Finally you can update your train spline with this data