Initiative w/ Advantage Via Item Mods

Hello all! So my player has a Sentinel Shield, which gives her advantage on initiative. We've had problems with this because the sheet won't take the item in question into account when she rolls for initiative. I was wondering if there is a way to add this via the mods section of the item in her inventory? Any suggestions are appreciated! For reference, I am using the Combat Master API script, which is what gave me the idea as my barbarian player will roll initiative with advantage by default via the cm API, but not our player in question.

There's nothing that specific for item mods, in fact they don't even do basic stat increases very well... There's an advantage toggle on the Roll20 5e sheet's Settings tab (if that's what you're using), or you can use a macro with an advantage query - there's a few of these about, but here's an example: @{selected|wtype}&{template:simple}{{rname=INITIATIVE ROLL}}{{mod=@{selected|initiative_bonus}}}{{r1= [[?{With advantage?|Normal, 1d20 | Advantage, 2d20kh1 | Disadvantage, 2d20kl1} + @{selected|initiative_bonus}@{selected|pbd_safe}[INIT] &{tracker} ]]}} {{normal=1}} {{global=@{selected|global_skill_mod}}} @{Selected|charname_output} I prefer using a macro, as the sheet version doesn't include global modifiers or an advantage query (inspiration, bless, bard stuff, other sources of advantage on dexterity checks etc. etc. etc.... there's a massive list of things which can impact your Initiative roll).

I figured out that my barbarian player has a initative-style in her attributes section that reads, {@{d20},@{d20}}kh1 So I simply added this into my paladins, the player who has the issue, attributes & abilities. It's not very versatile and when she exchanges her shield that gives her advantage on initiative for something else I will have to remove it, but for now it works.