How do I add non-witch spells to the witch spell list?

[grandpoobah]

I'm working on a special witch build which requires adding (wizard, magus) damage spells like corrosive touch and shocking grasp to the witch list.

Other than Witch Patron (elemental patron) and (samsaran racial feature), are there other ways to add non-witch spells to the witch spell list?

Here is the intended build:

one level dip in sorcerer for wild-blood/crossblood white dragon+water for +2 damage/dice cold damage.

Use winter witch archetype with Level 2 hex option to add cold damage to any touch attack.

Mix with Intensified shocking grasp and corrosive touch for hilarity. (or through snowballs at range).

Build would be for PFS play, so Samsaran is not an option, and Elemental Patron does not work with winter witch archetype.

[Aeric Blackberry]

Extremely few spells extremely late using Improved Eldritch Bloodline Arcana.

[Imbicatus]

Be a half-elf and take Bonded Witch. You get various non-witch spells depending on which item you bond.