Yearly Upgrade at Costco trading in different phone (still has EIP balance)

T-Mobile employees & more experienced customers: have Go5G Plus + Yearly Upgrade — keep current EIP/RDC and trade a DIFFERENT phone for iPhone 18 Pro at Costco? I’m on Go5G Plus , and my line has the Yearly Upgrade feature . Last year I purchased an iPhone 17 Pro on this line through T-Mobile EIP with promotional credits at Apple Store. The 17 Pro has now reached the point where at least 50% of its EIP has been paid. This year, however, I do NOT want to use the Yearly Upgrade early-payoff benefit . I don’t want T-Mobile to forgive the remaining 17 Pro balance, and I don’t want to turn in the 17 Pro. Instead, I want to: • Keep my iPhone 17 Pro • Leave its existing EIP active • Continue receiving its existing promotional RDCs making it effectively $0 • Preorder an iPhone 18 Pro through the T-Mobile kiosk at Costco • Trade in a Galaxy S25 Edge for the new $1,200 trade-in promotion ( Important : This S25 Edge has EIP on another line that doesn’t have yearly upgrade feature & is effectively $0 monthly after RDC) • Put the iPhone 18 Pro on a second EIP on the same line and still get $0 monthly My questions: 1. Can I use my Go5G Plus line’s Yearly Upgrade promotional eligibility for the $1,200 iPhone 18 Pro offer without exercising the early EIP payoff on my existing 17 Pro? 2. Can I trade the S25 Edge even though it still has an active T-Mobile EIP on another line , while leaving that EIP open and continuing to pay it? 3. If the S25 Edge’s EIP is currently receiving RDCs, would those credits continue after I physically trade in the device, assuming the EIP and its original line remain active? 4. Can the iPhone 18 Pro be placed on a second EIP on my 17 Pro line , with both the old 17 Pro EIP/RDC and new 18 Pro EIP/RDC running simultaneously? 5. If the S25 Edge CANNOT be traded because it still has an EIP, could I instead buy a qualifying used phone cheaply from Facebook Marketplace (or another third party) and use THAT phone as the $1,200 promotional trade-in? 6. Does the phone need to be traded in at Costco kiosk after receiving new phone or has to be sent to T-Mobile directly? Can it be traded in at T-Mobile corporate store instead? Ideally, my end result would be: • 17 Pro: I keep it; existing EIP + RDCs continue • S25 Edge: trade it if allowed; otherwise keep its EIP/RDC untouched • Alternative: buy a cheaper qualifying trade-in from FB Marketplace if necessary • 18 Pro: new EIP + $1,200 promotional RDCs • No early EIP forgiveness on my 17 Pro Finally, does preordering through the T-Mobile kiosk at Costco change any of these rules, and would I still receive the applicable Costco Shop Card/member benefit ? I’d especially appreciate answers from current T-Mobile/T-Force/Costco T-Mobile employees familiar or customers who have actually exercised it, with Yearly Upgrade SOC on Go5G Plus, multiple EIPs/RDCs, and third-party trade-ins . My biggest concern is making sure the Costco rep doesn’t accidentally process this as an early Yearly Upgrade payoff and close my existing 17 Pro EIP/RDC. Thanks!