Waheguru ji ka khalsa
Waheguru ji ki fateh
ad granth and SGGS ji is the same thing just in SGGS ji bani of 9th guru was added by guru gobind singh ji and when dhir mal declines guru ji to give ad granth then guru ji writes SGGS ji by memory. Although writings of guru sahibs are drown in battle of sirsa but still guru ji never added anything from his writings. It should be some reason. After guru sahib bhai mani singh and other guru sikh collects guru sahibs writings.
SGGS ji is in gurudwaras bcos we have instructed by guru ji that "sab sikhan ko hukam hai guru maneyo granth" and there is only one granth at that time. We have to respect dasam granth also as there is guru gobind singh's bani in it. We cannot do prakash of dasm granth in front or SGGS ji bcos there is only one guru and also this is written in Sikh Rehat Maryada made by Akal Takht Sahib.
As I answered before we have to respect dasam granth also but not as SGGS ji because there is only one Guru.
Please forgive for any mistakes or any wrong things if have write there.
And sorry for english which is not correct....
Waheguru ji ka khalsa
Waheguru ji ki fateh