Kevin Federline previously told ET through his attorney that the kids won't be at their mom's nuptials.
"Kevin is absolutely not interfering in any way with Sean Preston and Jayden James’ decisions to not attend Britney and Sam’s wedding," the source tells ET. "It has nothing to do with him. They are 16 and 15 years old and made the choice themselves. The wedding is a bit overwhelming for children of their age, and they preferred not to go."
Mark Vincent Kaplan, Federline's powerhouse attorney, previously told ET that Jayden James, 15, and Sean Preston, 16, "will not be going to Britney and Sam's wedding" on Thursday. Spears and Federline, who share the two teens, were married from 2004 to 2007.
"Although the boys will not be in attendance, Kevin and the boys are happy for Britney and wish her and Sam all the best going forward," Federline's lawyer says. "They are excited that this will be a positive development for her post-conservatorship life."
"Kevin and the boys want her to be happy," he adds of Spears. "Hopefully this will be a key for her to be happy and remain happy going forward. They all feel that this is Britney and Sam's day and nothing should take away from that."
As for the rest of Spears' family, a source tells ET that "Britney's mom [Lynne Spears], dad [Jamie Spears], and [sister] Jamie Lynn were not invited" to the singer's nuptials.
"Ever since Britney and Sam talking about getting married and planning their wedding, inviting them was never a question," the source says.
Of the wedding itself, the source tells ET, "Britney and Sam are getting married today in a small ceremony at her home in Thousand Oaks."
"They are so excited," the source adds of the couple, who announced their engagement in September. "They have felt like true partners for a long time and can't wait to officially be husband and wife."
This will be Asghari's first marriage and Spears' third. In addition to Federline, Spears was briefly married to former friend Jason Alexander in 2004.