Hey Heather85, you must be confusing her with Missi Pyle's character Natasha, who began on the show in season 4 as Emily's biological mother who Christy helps to regain custody. They are both tall and blonde so maybe that confused you. Hope that clears it up.

Missi Pyle (Natasha) was in 5 episodes: S4E21, S5E01-S5E04.

Kristen Johnston (Tammy) appeared for the first time in S5E17 and became a series regular in season 6 and 7.

Here you can see both actresses on the TV show "The Exes (2011-2015)":

S3E03 "Trading Places" - videoclip

Wonder2Wonder, that's pretty funny that they were both on The Exes. Come to think of it, Johnston and Wayne Knight were both on 3rd Rock from the Sun and Johnston and French Stewart were both on 3rd Rock from the Sun and are both on Mom lol.

@KDawg39 said:

Wonder2Wonder, that's pretty funny that they were both on The Exes. Come to think of it, Johnston and Wayne Knight were both on 3rd Rock from the Sun and Johnston and French Stewart were both on 3rd Rock from the Sun and are both on Mom lol.

Yes, it's fun seeing those two together on the same show.

• I got to work with my beloved ⁦@FrenchStewart⁩ this week on ⁦@MomCBS⁩!!! 💜 -@kristen johnston

• S7E13 "Dammit Sandra and the Money Bus" - videoclip

@wonder2wonder said:

Missi Pyle (Natasha) was in 5 episodes: S4E21, S5E01-S5E04.

Kristen Johnston (Tammy) appeared for the first time in S5E17 and became a series regular in season 6 and 7.

Here you can see both actresses on the TV show "The Exes (2011-2015)":

S3E03 "Trading Places" - videoclip

When I wrote that post, I didn't completely understand the storylines and which was which because they hadn't told us a lot about either character at that point. But I caught on quickly and realized who was who and what was what. :D