Squishy belly- should I gain?

[Bigbellychick]

Basically I'm quite small/slim but I want to gain on my belly because I like having a soft squishy belly (and I like my food hehe) so I was wondering what you guys think- should I gain and if so how much and how should I best do this?
Thankyou and I'm about 140 at the moment

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[Tracii]

 

[dblbellybhm]

 

[bbwbud]

 

[Bigbellychick]

 

[bbwbud]

 

[Lear]

 

[SSBHM]

 

[BigFA]