we have to consider lagna as present life, children’s are futures of native 5th house and native himself being future of his father 9th house holds correct. I agree to this logic. Lagna 5th and 9th all are trine to each, a triology of past present and future. If we move a trine backward its 9th house , the past and if we move a trine forward we land in future, future is yet to come and past is already passed. Lagna or present  is equidistant from past life and future life. Since karma is cyclic in nature we keep moving from 9th to lagna and then 5th in pre defined karma cycle with no easy escape. Only when lagna 5th lord and 9th lord strongly placed in either 1 5 9 or 6 8 12 complete discharge of karma has occurred and there is no re birth or native will attain moksha.  Noramlly this combination will be seen in pravajya yoga. or sanyas yog

Another logic to this theory is

Ist house indicates self or soul 4th is mind or thought 7th is desire or kaam and 10th is action we take to fulfill. Desire rose due to mind in reverse order ..10  7   4 and lagan ..kendra sthana. This are the house of mad (ist) moha (mind) kaama (7th) 10th (lobha)    Similarly if 9th house is past lagna then 12th house indicate mind 3rd is desires and 6th house action taken for fulfillment in previous birth.  Since 5th house is future birth,  8th house 11th house 2nd house indicates karma accumulation for next birth. 2nd house is bank balance which we carry to next birth only difference is carriable stuff is only dharma. In same way 10th house indicates what  we got from past birth and how we utilize it fwd journey to next house ( 5 sign ) or back ( 5 house) 6th house of suffering. Roga rina ripu. A repetition of karma cycle till we change.

Trik lords . 6th  action  of past birth majorly native suffers due to debt disease and enemies bcoz of fructification of actions taken to fulfill desire. This can be remedified. ,  12th mind of past birth and 3rd unfulfilled  desired of past life and  hence most of karma clearence is done by this lords. Likewise 5th house is dharma fallowed by us in past birth forms classical dhan yog or rajyog. To be enjoyed in this birth.

Rajyog caused by combination of kendra and trikona, kendra works on deha and trikona works on aatma, combination of this gives pleasures to deha and peace to soul.

3rd house is house of efforts  from lagna actually total movement of life to fullfill desires.

11th house is total movement to fulfill desire of past birth which we succeed or not in this birth.

11th achivements or left over desires for next birth bcoz it happens to be 7th from 5th. A continius process.

Now 3 6 10 and 11 th houses also called as houses of growth bcoz it continues from birth to birth and very important component of vasumati yog. If there is relation of 3rd and 11th lord , person is fulfilling desire of life supported by lagna lord. 1 3 and 11.. Person is in perfect tandem of his past birth karma cycle.

And if we move 3 house backward it is 11th house nothing but efforts of past birth . And it is 3rd to 9th past birth.

There is kendra, 1 4 7 and 10 in which works on physical plane with lagna also carries essence of trikona or past and future birth links. Likewise it becomes most important. Similarly 11th 3rd and 7th is also trikona in which only 7th happens to be kendra lord which has link to desires or can say collective desires.

Same way 3 6 9 and 12 house are in kendra to each other in which only 9 has differentiality. Note worthily is which ever trine u pick, kendra  trikona or panapara  u will find one house being different and links to other trine or kendra chain.