WooCommerce BOGO & Variations Update

I need two focused tweaks made to my live WooCommerce store and I want them implemented cleanly so nothing else on the site or in the checkout flow is disturbed.

Buy 2, Get 1 Free
• The offer applies to specific items only; I’ll give you the exact SKUs.
• When a shopper adds any two of those items and enters the promo code, WooCommerce should drop the third one (same SKU) into the cart automatically, show the correct discount, and carry that logic all the way through to the thank-you page.
• The code may be used on all items I specify; it shouldn’t affect anything else in the catalog.

Product variation merge
Right now the same product is listed twice—one 20 mL, one 30 mL. Please convert these into a single variable product so customers select the size from a simple dropdown instead of hopping between listings. All existing reviews, images, SEO slugs, and stock data must remain intact.

Acceptance
1. I can trigger the BOGO on the specified SKUs and see the free item auto-added.
2. The variable product shows both sizes, purchases correctly, and the front-end design and checkout experience look exactly as before.
3. No other plugin, theme, or payment setting is modified.

I’m running the latest stable WordPress and WooCommerce versions and have full admin access ready for you. Let me know your estimated turnaround time and any quick questions you still need answered.