LSU sorority history question

[ADPiEE]

Just curious.....

I saw on Irishpipe's threat that this is the history at LSU:

Louisiana State University
Baton Rouge, LA

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Kappa Delta Epsilon 1909
Alpha Delta Pi Omega 1914-1985
Delta Zeta Sigma 1917
Sigma Delta Tau Zeta 1924-1969
Chi Omega Phi Gamma 1924
Alpha Chi Omega Beta Gamma 1926-1970
Phi Sigma Sigma Omicron 1927-1933
Beta Sigma Omicron 1929-1964 National absorbed by ZTA, LSU chapter released to Alpha Phi
Delta Delta Delta Delta Omega 1934
Phi Mu Alpha Eta 1934
Kappa Kappa Gamma Delta Iota 1935
Pi Beta Phi Louisiana Beta 1936
Alpha Epsilon Phi Alpha Theta 1938-1984
Alpha Xi Delta Beta Iota 1938-1988
Alpha Omicron Pi Alpha Omicron 1938-1980
Delta Gamma Gamma Zeta 1948
Zeta Tau Alpha- Delta Kappa 1959
Kappa Alpha Theta Delta Kappa 1963
Gamma Phi Beta Gamma Lambda 1964-1977
Alpha Phi- Delta Tau 1965-1980/Recolonization Fall 2013
Alpha Gamma Delta Theta Alpha 1979-1985
Sigma Kappa Zeta Omega 1984-1993

My aunt was a BSO at LSU in the 50's and I saw that this group was absorbed by ZTA . I'm assuming that this happened in 1959 because it looks like that is when ZTA started according to this list.

My aunt's daughter was a ZTA at LSU in the 80's and I had just assumed that she was a legacy.

The part I'm confused about is where it says the LSU chapter of ZTA (?) was released to Alpha Phi.

Does anyone know anymore detailed history about the order of how this all happened?