The main issue you have is the SIM card size mismatch b/t the Pixel (nano) and the S5. I would call Verizon and tell them you are getting iP6's for L1 and L2 and need them to mail you nano SIMs for the iP6's.
Then also order SIM card adapters from amazon or ebay - don't get the Noosy's and make sure you order from a US shipper so that the adapter gets to you soon. If you do that today, you should have those by Wednesday of next week. Also buy some double sided scotch tape. I have used these before and they work fine:
https://www.amazon.com/iSYFIX-Standard-Adapter-Converter-Complete/dp/B017TB2668
Once you have received those, power down L1 and L3's phones, log online and do a switch device b/t L3 and L1 to get the iP6 active on L1 and the S5 active on L3. Turn the phones back on, leave them on those lines for about an hour, make calls/texts and log back online to see that they system has updated the phones on the lines.
Then power down the phone again, put a piece of double sided tape in the nano to micro SIM adapter, put the iP6 nano SIM in the adapter and then put the adapter + nano SIM in the S5 and turn it on. Then log on and do an Activate/Switch device to activate the iP6 on L3 using one of the nano SIMs that Verizon mailed to you.
Repeat that same process b/t L4 and L2 to get a nano SIM active on L2.
Now you will have nano SIMs active on L1 and L2 in adapters.