After reviewing the visitation rules for all the Dallas County facilities in Lew Sterrett, the terms are not clear for a car seat.  They do however prohibit child strollers and toys.

In the Dallas County sheriff's office there is a complex known as the Lew Sterrett Justice Center.  There are three individual jails within the complex - The North Tower Detention Facility, West Tower Detention Facility and Suzanne Lee Kays (South Tower) Detention Facility - you will have to follow the visitation rules and proceed accordingly.

You have to send it by regular mail it back to them - Uintah County UT Jail. Once they have the application, they run it through the system to make sure that the visitor does not have a criminal record before approval.

The friend you speak of that is not approved cannot visit without prior authorization. Your inmate may add or subtract potential visitors to his list as often as he wants. 

The visitation for juvenile facilities is strict and might be limited to family members only. There are other restrictions that come in play depending upon the offense level of the person you are wishing to visit

Inmates cannot receive calls in ANY prison or jail. Writing a letter is the only way for you to initiate contact, the telephone call MUST be initiated by the inmate from the prison.

Most prisons and jails have an array of vending machines. Make sure that you bring plenty of change and one dollar bills. Don't let the inmate handle the money, the guards may cancel your visit.