Retirement tax questions

Hello, Good Morning,Since fidelity doesn't know which year I made  contribution in IRA is deductible and which contribution is non deductible I will get taxed on the how much amount I convert into Roth IRA right? and then once I file taxes, portion of the conversion I can track through form 8606 right and once I put numbers in turbotax, will turbo tax calculate deductible and non deductible portion ?  what happens if I don't convert in to Roth IRA and open an another new  traditional and Roth  IRA account with new company lets say Charles Schwab(currently I have account with Fidelity) and make traditional IRA non deductible contribution for 2024 and the convert to Roth ? Thank you very much for helping me out.I really appreciate for your help!