Answer

In Jain tradition, King Siddhartha Raja is well known as the father of Bhagwan Mahavir, the 24th Tirthankar.

However, the name Samarveer is not a widely established or commonly referenced name in the standard Jain accounts related to Siddhartha Raja and Bhagwan Mahavir.

So, I cannot state a definite relation between Samarveer and Siddhartha Raja unless you clarify which Samarveer you mean or from which Jain text, story, or tradition this name is coming.

Takeaway

Sorry, I can only provide information that is clearly established within Jain tradition.