subbing in Meta field title when field is complete

[Shaun6561]

Hello, 

I want to sub in the standard title for a product meta field when the field is completed. So without the metafield completed the title defaults to a standard title of 'Pairs well with', but when the meta field is complete the title is sub-in to replace the standard title. I have tried a number of ways but can't get it to work.

Meta Field title:

product.metafields.custom.cross_sell_title

Orginal code:

<div class="upsell__holder" data-upsell-holder data-add-action-wrapper>
<h2 class="upsell__holder__title">Pairs Well With</h2>
<div class="upsell">