You are subject to Park / Tier restrictions until you tap into any one of your LLs on the day of your visit. So scanning into the park has no effect on what you can book - you are still subject to the rule of only having up to one tier 1 and two tier 2s in the same park.
But as soon as you tap into your first LL attraction, then you can book / modify additional Tier 1s or attractions in another park, including the two remaining prebooked attraction slots.
So the best strategy is to book a Tier 1 for the morning and actually use it early on so you can start booking and modifying to attractions you really want if they were not among your Tier 2 options.
I read through it. Well done! Thank you!
Thanks so much Jeff!
When will the touring plans be updated to incorporate lightning land multipass and lightning land single pass?
Len said in another thread that it was “almost ready.” Keep checking back!
Thanks for the summary!
Another thought (as I exoerienced pre-booking, yesterday). Since Tier 1 9:00am park.opening LLs are limited and hard to come by, it might be more beneficial to lock in any LL at park open, simply to unlock the additional Tier 1 booking opportunity as quickly as possible. So, I’d book at least 2 LLs up front: the limited supply Tier 1 (for the earliest arrival time available) and a Tier 2 for 9am.
Also, since Disney controls the initially suggested order logic, and you waste valuable time and effort trying to maneuver the order and time availability, I might be inclined to quickly purchase LLMP with just one Tier 2 preselecr locked-in at 9am. Then, immediately after purchase, go back in and add the first slot available for Tier 1. Then, either add the 3rd pre-selection, or wait until I tap in at 9am to book the 3rd (and 4th).
In hindsight, I got “stuck” with Tier 1’s in the late 9 o’clock hour (e…g. 9:40am) and the system won’t let me shoehorn an otherwise available Tier 2 LL in front of it at 9am.
Good strategy too! If you’re not park hopping, you could also save the prebooked Tier 1 for the early afternoon.
You have to have a shared plan (resort reservation, ADR) or add a note and tag both people. I just add a note (on a desktop, not sure if it can be done in the app). Go to plans > Add more plans > Notes (the last option in the drop down menu.
Oh that’s an interesting problem I hadn’t thought of. 
Good feedback!
Ooh, I hadn’t seen this anywhere else. That’s a good one and important too!
I am guessing that will be the same for all non-dated tickets?
Love the ability to modify these LLSP!
Earlier materials said you could switch dates up until the point you tap in, so I would assume this is the one limitation!
Thank you!! 
You’re awesome.
I don’t know if you have seen this thread - it gets into the weeds on hacks and work arounds like the one you were suggesting. I thought you would probably find the discussion interesting (I would skip to the posts after the 24th!)
https://forum.touringplans.com/t/the-lightning-lane-multi-pass-advanced-strategies-thread/100361
Is it advantageous to keep slots open?
What’s the priority across parks? For example, should I prioritize SDD over TBA?
I don’t see the point of this unless you can only get Kate times since as soon as you use the first you can book another.
Do we know yet if you can let the first expire and then book another or does it have to be used?
You can let the first expire, but you can only book another if you have already tapped into the parks. You can still use the expired one within the grace period.
Edited - this information is not correct. This only works if you have tapped into your first LL of the day, NOT after you tap into the park.
I have to say I am suprised at how quickly those SP are selling out. At the 3 day mark for offsite and AP many are sold out. Disney is juat printing money on those things. $22 for ROTR is more than all of AK!
I also think they are going to need to resguffle these tiers slightlty - move more into the Tier 2 catagory, or let people book 2 Tier 1 if they choose. POC, HM, TSM and TOT should not be the hottest tickets in town.